The link between surgery in the elderly and persistent postoperative cognitive dysfunction has been the subject of considerable debate. Intellectual impairment is common among elderly persons in the days after surgery and persists in a small proportion of cases. The frequency of persistent impairment (5 to 57 percent) and the degree of deficit vary greatly and are related to several factors (1,2). Methodological shortcomings in published studies have led to inconsistent findings (1,3), and long-term sequelae beyond about ten months have not been studied (3).
Several important hypotheses have not been explored adequately. For example, the nonidentification or exclusion of possible cases of dementia or neuropsychiatric disorders has precluded exploration of the hypothesis that surgery and anesthesia may provoke or accelerate cognitive impairment among elderly persons who have preexisting neuropathology (1).
In the forensic case presented here, a court was asked to determine the relationship between surgery and postoperative mental decline in an 81-year-old woman who had preexisting mild cognitive impairment and subcortical vascular disease. The woman sustained injury as a pedestrian in a motor vehicle accident in New South Wales, Australia, and was the plaintiff in a damages case; the defendants were the driver and the owner of the car. In relation to proceedings pursuant to the Motor Accidents Act 1988 (as amended) (4) for the awarding of damages for noneconomic loss—pain, suffering, and loss of amenities and expectation of life—I was asked by the plaintiff's solicitors to write a report describing the relationship between the accident and the plaintiff's mental decline and time to institutionalization and predicted death.
Mrs. L was an 81-year-old widow living in a retirement village. She had a three- to four-year history of poor short-term memory and mild disorientation, but her conversation skills were considered excellent and her behavior appropriate. She was described as being independent in activities of daily living and required minimal care. She could shower, dress, and cook for herself. She kept her room tidy, knew the village's meal times, and could move to and from the dining room independently. She was able to catch a bus to the local shopping center, shop independently, and book and attend social bus trips arranged by the retirement village. She knew the staff by name and also knew their functions at the village.
Mrs. L had a history of ischemic heart disease, for which she had undergone coronary artery bypass grafting more than ten years earlier, and breast cancer, for which she had undergone a left mastectomy many years earlier.
In late 1998 Mrs. L was knocked down by a vehicle being driven in reverse. When the ambulance arrived at the scene, Mrs. L was alert and oriented, her eyes were open, and she was able to comply with commands; she received a score of 15—the maximum score—on the Glasgow Coma Scale (5). The report of the emergency personnel noted that she did not lose consciousness. When Mrs. L arrived at the local hospital, the triage team observed no injuries except a fractured left neck of femur. There was no external evidence of head trauma.
On the same day, Mrs. L underwent surgery involving an open reduction and internal fixation of the femur with the insertion of a pin and plate. She required a blood transfusion. Her postoperative period was complicated by a deteriorating mental state. A computed tomographic brain scan indicated ischemic changes and frontotemporal atrophy. The results of other investigations—a full blood count with electrolytes, a hemoglobin test, a liver function test, a thyroid function test, and vitamin B12 and folate measurements—were unremarkable.
Thirteen days after her surgery, Mrs. L was transferred to the rehabilitation ward and was described as confused and disoriented. She received a score of 11 out of a possible 30 on the Mini Mental State Examination (MMSE). Her cognitive impairment was moderately severe throughout the admission, which prevented rehabilitation. She could not learn new techniques for walking and was unable to carry through a full rehabilitation program as a result of her moderately severe dementia. When Mrs. L was discharged, both the physiotherapist and the nursing staff said that she had been very confused and agitated, had shown limited progress, and needed direction and supervision. She required prompting for most simple tasks, was unable to follow instructions, and required supervision for all activities of daily living.
Six months later, having been admitted to a nursing home, Mrs. L continued to need the assistance of staff to get dressed, undressed, washed, and groomed. She was confused about time, place, and person. She had major difficulty with communication, particularly comprehension. She needed prompting to eat and drink as well as help opening food packages, and her food had to be cut up for her. She required a walking frame for mobilization and needed to be accompanied by staff when walking. Her local physician noted that her mental state, particularly her conversational skills, had deteriorated significantly since the accident. Mrs. L could no longer care for herself, was dependent on staff and family members for constant care and attention, and no longer went out.
Two years later, having deteriorated slowly over time, Mrs. L continues to be reliant on staff for almost all instrumental and basic activities of daily living. Specifically, she requires complete assistance to shower, dress, and use the toilet. She requires prompting and direction to attend the dining room for meals, although she can feed herself. She moves around with a walking frame or a wheelchair and is not capable of any independent activity outside the nursing home. At the time of assessment, Mrs. L's medications included 80 mg of furosemide daily, 150 mg of ranitidine twice daily, 20 mg of tamoxifen daily, 1 mg of lorazepam daily, and 5 mg of enalapril daily.
On examination, Mrs. L presented as a casually but neatly dressed elderly lady sitting in a wheelchair. She was transferred to her room in the wheelchair. She was pleasant, cheerful, and cooperative within the constraints of a severe language disturbance with both expressive and receptive components. She had obvious word-finding difficulties. She was unable to give a history. She was disoriented as to time and place and said that she had already had lunch when this was clearly not the case. She received a score of 9 on the MMSE. Her score on the orientation items was 0, and she recalled none of a possible three items after a distraction task.
Although her performance was to some extent confounded by her communication difficulties, Mrs. L could comprehend instructions sufficiently to demonstrate a relative preservation of more posterior praxis tasks, compared with her more severe language disturbance. When asked to draw a clock face, Mrs. L initially drew a circle within the circle, then drew in the numbers one, two, three, and then four, which she turned into a rectangle, and perseverated on drawing a pattern around the rest of the clock face. Physical examination revealed a carotid bruit and a marche-à-petits-pas gait. She also had osteoporosis of the spine with kyphoscoliosis due to multiple vertebral fractures and degenerative disease. A diagnosis of severe vascular dementia was made.
It was argued for the plaintiff that at the time of the accident she had suffered from mild cognitive impairment on the basis of her mild memory impairment in the absence of functional decline (6). The temporal relationship between surgery and Mrs. L's precipitous decline in cognition and functional capacity suggested that she had suffered perioperative cerebral insults that had prematurely accelerated her mild cognitive impairment. Under Australian law, one of the legal tests of causation is whether the consequences—that is, the surgery and its complications—of the "Tortious act"—the accident—were foreseeable. Thus the plaintiff could claim that damages were related to the accident because the surgery and its complications were foreseeable consequences of the plaintiff's being hit by a car (7).
The other important forensic issue was to distinguish Mrs. L's course after the accident from the natural progression of her disease. Predicting expected time to institutionalization for a patient with mild cognitive impairment is often difficult because of the heterogeneity of this condition and its variable course—time to onset of dementia ranges from four to ten years (6,8)—and conflicting evidence in the literature about predictors of placement in a nursing home (9). Furthermore, there is some controversy as to whether people who have mild cognitive impairment associated with subcortical or white-matter disease have a low (10) or high (8) rate of decline.
Nevertheless, the mild severity and low rate of decline documented before the accident and the precipitous decline afterward suggested that the surgery significantly hastened the time to Mrs. L's institutionalization and shortened her predicted survival time. It has been shown that the rate of deterioration and the severity of illness influence the length of time to nursing home placement and death (9). Thus a much more favorable trajectory would have been predicted for Mrs. L had she not been involved in the accident. In addition, Mrs. L's curtailed ability to walk as a result of the accident would have contributed to her poor predicted survival time (11).
The court found that the evidence pointed to the surgery as the "process that caused her brain that extra damage that propelled her into dementia in a florid form" and "turned a mild state into full-blown dementia." The court did not accept that Mrs. L's "postsurgery manifestation of dementia was transient and resolved." It considered that, in the absence of the accident, Mrs. L would probably have continued to live a relatively independent life within her retirement village for four years after the date of her accident. The court concluded that the effect of the accident on the plaintiff was "nothing short of devastating" and assessed the severity of the case at 45 percent of that of a most extreme case, incorporating a discount factor for the plaintiff's advanced years.
This case report presents a convincing description of the exacerbation of cognitive decline after surgery under general anesthesia. The fact that this decline occurred in an elderly woman who had preoperative ischemic brain changes and mild cognitive impairment supports the hypothesis that surgery and anesthesia may hasten the course of neuropsychiatric disorder (1). Ancelin and colleagues (12) similarly found that preoperative cognitive impairment was a risk factor for cognitive dysfunction after surgery.
In particular, persons with vascular disease—or, more specifically, subcortical disease—may be particularly vulnerable to factors such as alterations in cerebral blood flow during surgery. An association was found between intraoperative blood loss and a drop of 20 percent or more in blood pressure and postoperative functional decline in a population with a high incidence of preoperative hypertension (2). Alterations in blood pressure regulation and rapid reductions in blood pressure have been proposed as potential contributors to white-matter changes, particularly among patients with hypertension and leukoaraiosis (13).
Notwithstanding some of the specific aspects of Australian law, many of the forensic issues related to civil law and damages that have been discussed here have wider application. In particular, the potential for damages to be awarded for postoperative mental decline is of great interest in light of the debate about the effects of surgery on the mental status of elderly persons. The contribution of medical professionals in providing their opinions about this and other controversial issues discussed here, such as those related to disease course in mild cognitive impairment, illustrates the advancing edge of forensic geriatric psychiatry.
The author thanks Alan Lakeman, B.A., L.L.M., and Libby Moss, B.A., L.L.B., for their assistance regarding the legal aspects of this case.
Dr. Peisah is a consultant psychiatrist in private practice and a research fellow in the department for old age psychiatry of the Prince of Wales Hospital, 256 Edgecliff Road, Bondi Junction, NSW 2022, Australia (e-mail, email@example.com). Marion Z. Goldstein, M.D., is editor of this column.