Medial Temporal Lobe Amnesia: A Case Study for Nursing.
Memory problems are a serious and frequently encountered clinical entity. They interfere with most aspects of life, especially safety and independence. This article describes the medial temporal lobe (MTL) structures involved in memory and reviews the research on amnesia that led to their discovery. Finally, a case study of a patient with amnesia demonstrates how nurses can use these research results to select the most appropriate assessment tools and guide development of nursing therapies.
Amnesia is an intriguing clinical and scientific entity, but also a profoundly debilitating problem. A person may lose some or all memories prior to the causative event (retrograde amnesia) or be unable to form new memories from the onset of the event (anterograde amnesia). Damage to MTL structures (the hippocampus, entorhinal, perirhinal, and parahippocampal cortices), especially the hippocampus, is consistently associated with anterograde amnesia. To a lesser extent, these same structures are responsible for retrograde memory loss limited to about a 2-year period. A number of other brain structures may contribute to retrograde amnesia; these include the perirhinal cortex, medial forebrain, and diencephalon. Primary ischemia is the most likely cause, attributable to infectious processes, traumatic brain injury, and tumors. It is possible for a person to experience both retrograde and anterograde memory loss, known as global amnesia.[1,2]
Memory loss may be due to psychological factors or, more commonly, to organic disruption. Although this paper focuses on organic processes underlying amnesia, note that psychogenic forms of memory loss present in a similar fashion. However, psychogenic amnesia tends to follow an emotional crisis. It affects remote as well as recent memory, sometimes erasing remote memories more than recent ones. The person might even lack self-recognition.[1,2]
The most dramatic type of memory loss is transient global amnesia. This is the sudden onset of memory loss lasting from as little as 30 minutes, to as long as 12 hours or more. The person may be totally disoriented except to self, with a retrograde memory deficit that may extend back many years. There is usually total recovery.
Over the past 100 years researchers studying amnesia have made great strides in uncovering the structures and functions of the MTL memory system. A review of these discoveries of amnesia with organic origins can help explain Mrs. N's symptoms and provide a basis from which to prescribe nursing therapies.
History of the MTL Memory System
Many years ago, structures in the MTL were considered obsolete remnants that would disappear as man evolved. Today we understand the importance of these brain areas in regulating memory, mainly because of the scientific study of patients with medial temporal lobe lesions.
The Work of Scoville and Milner
Cases associating MTL damage with memory problems have been reported since about 1900. Amnesia following MTL injury caused by viral encephalitis, posterior cerebral artery occlusion, and ischemic injury has been documented. The case that firmly established the MTL as an essential site for normal learning and memory functions, however, was that of the patient HM. As a young man, HM developed intractable seizures that remained resistant to conservative treatment. Because unilateral temporal lobectomy was an effective treatment for seizures at that time with few adverse effects, surgeons reasoned that bilateral temporal lobectomy should also result in few adverse symptoms. So in 1953, Scoville performed a bilateral temporal lobectomy including partial removal of the hippocampus.
HM's recovery from surgery was uneventful except for one thing--he could not make any new memories. Everything in his environment was always new to him. Interestingly, this memory dysfunction seemed to be his only problem. Other cognitive functions were spared, including his intelligence with a good vocabulary and normal language skills. His memory prior to his worst seizure years was intact. He retained immediate recall, and his psychomotor skills were preserved.
Milner, a neuropsychologist who was studying the effects of temporal lobe lesions on memory, examined HM, testing his memory, perception, intelligence, and visual-motor skills. Her careful testing of this patient with a known, specific, surgical MTL lesion brought out these important findings:
* Memory is a neurological function.
* Memory is distinct from perception and intelligence.
* MTL memory loss is a pure amnesia--no other deficits are present.
* MTL structures surrounding and including the hippocampus have a narrow and specific role in memory.
Milner also studied many patients with unilateral injuries, including many patients who had epilepsy and removal of one medial temporal lobe. She developed tests that brought out the particular deficits caused by lesions of the right MTL versus lesions on the left, dominant side of the brain versus nondominant, and was thus able to delineate the contributions made by each side. Persons with a MTL lesion on the dominant side of the brain (for instance a right-handed person having a left MTL lesion) suffered more problems with verbal skills. Those with lesions on the non-dominant side of the brain (a right-handed person with a right MTL lesion, for instance) had more problems with spatial location and image recognition. These findings are listed in Table 1. Milner's group of patients showed varying degrees of memory impairment. Many times, the patients with unilateral surgeries already had sclerotic and nonfunctional lobes on the opposite side. Milner reported that the severity of the deficit usually showed a positive correlation with the amount of hippocampal damage at autopsy.[8,9]
Table 1 Research Data on Memory Deficits From Unilateral MTL Lesions Right MTL or Left MTL or Nondominant Dominant Problems Problems Spatial location Word-finding Spatial learning Names Facial recognition Sensory hallucinations Learning from images Verbal learning
Another case, RB, sheds more light on the function of MTL learning and memory. RB suffered cerebral ischemia during coronary artery bypass surgery. Like HM, he too was unable to learn and create long-term memories. This was his only resulting cognitive deficit, and it was less severe than HM's situation. When RB died in 1983, extensive postmortem studies of his brain revealed bilateral lesions confined to the hippocampus. Other structures formerly considered necessary to cause amnesia were intact. This case established the fact that hippocampal lesions by themselves cause a clinically significant though less severe amnesia.
Although these cases have been helpful in localizing memory structures, as well as determining some functions, studying human cases has limitations. Researchers have had to rely on naturally occurring problems, because inflicting lesions on healthy brain tissues is, of course, unethical and unacceptable. Also, most human studies have not been quantitative, but have consisted of observations and the impressions of the researchers.
Therefore, scientists turned to animals for experimentation. After many years of working to study the same type of memory in animals as in humans, a monkey model of amnesia was developed.[8,9,10,11] With this discovery, researchers were able to apply surgical lesions to selected sites in the monkey's brain, introduce memory tests, and quantify the results. This has helped to identify the specific brain structures that must be damaged to cause amnesia (Fig 1). The memory test used most frequently with monkeys is the delayed nonmatching to sample test developed by Mishkin. In this test, two items, such as a ball and a shoe, are shown to the monkey. Then they are briefly taken out of sight. The tester replaces one item, for instance, the shoe, with a new one, such as a cup, and presents the pair of objects to the monkey again. The animal is rewarded when he picks the "nonmatching" new item, the cup. Normal monkeys readily learn this game and can pick the nonmatching item, even after many minutes of delay. Monkeys with MTL lesions, however, do well only if the delay is very short (seconds). They are severely impaired if the delay increases from a few seconds to several minutes and if they are distracted. This emphasizes that lesioned monkeys cannot convert short-term memory into intermediate or long-term memory.
[Figure 1 ILLUSTRATION OMITTED]
These animal studies have added a great deal to MTL memory knowledge, including two important discoveries:[10,11]
* Bilateral hippocampal lesions alone cause memory loss, but not as severe as HM's.
* Complete anterograde amnesia, like that of HM, involves not only the hippocampus, but also the cortical areas around the hippocampus, the entorhinal, perirhinal, and parahippocampal cortices.
Because of the morphological, physiological, and behavioral similarities of hippocampus in humans and animals, much can be learned about human memory from animal models. Scientists, including nurses, continue to experiment with monkeys and rodents. In one study, rats given bilateral entorhinal cortex lesions take longer to learn a spatial memory task (finding their way to a platform in a water maze) than control animals. Normal animals can usually swim directly to the platform by the second day of trials, while lesioned animals show much slower progress.
Current understanding of amnesia and memory systems has evolved from the data and observations revealed by these human and animal studies. It seems that memory is not one single process, but a collection of processes, and only one of these is impaired in pure amnesia. This research has also defined the conceptualizations of short-term and long-term memory and further distinguished procedural from declarative forms of memory (Fig 2).
[Figure 2 ILLUSTRATION OMITTED]
The type of memory that is impaired by MTL problems is the memory for facts and events.[9,11] This type of memory is called declarative, or explicit, because facts and events remembered through this system can be made available to a person's consciousness, "declared" to others, or used when needed. The terms short-term (learning and consolidating new memories) and long-term (retaining and remembering) memory apply specifically to declarative memory. Lesion studies show that the type of declarative memory impaired in amnesia is long-term memory.[9,11]
Short-term memory is the ability to recall verbal information immediately after it is presented. Examples include repeating a digit span of six numbers or copying a block tapping pattern. There are two limits to short-term memory:
* It can handle only a limited amount (5-7 pieces) of information at one time.
* It holds information only until a delay or distraction occurs.
Persons with MTL amnesia retain short-term memory. HM could repeat digit spans of six numbers normally. He could not improve by remembering longer spans, even after many trials, while normal subjects could remember spans of 20 numbers after the same or fewer numbers of trials. He could also repeat patterns on blocks, in a manner somewhat like the modern musical pattern game, Simon. He could not remember the test period from the day before, however. Evidently, short-term memory is mediated by a different system than the MTL, but the medial temporal system is necessary to put information into more permanent storage.
Procedural memory is the memory that is contained within learning skills or procedures. It is spared in amnesia. Procedural memory is expressed by performance. Research on amnesic patients, including HM, shows that these persons retain previously learned perceptual motor skills like riding a bicycle and are able to improve existing skills. They can also learn other cognitive tasks such as how to put together a jigsaw puzzle. The important point here is that although HM improved from day to day in a task, such as mirror writing, he did not remember the previous day's testing session.[9,11] Evidently, the MTL structures damaged in amnesia play an essential role in long-term memory, but their destruction does not prevent a person from having procedural memory or from acquiring new psychomotor skills, Procedural memory is sometimes called implicit memory because it is more of an unconscious phenomenon.
Evidence indicates that the MTL is required to maintain the input of events, happenings, and data as long-term memory.[9,11] The neocortex perceives events in verbal, auditory, and visual modes. These can be elicited without the MTL on a short-term basis. However, if the system is overloaded or if time intervenes, without MTL activation these receptions are lost. The MTL system has many reciprocal projections in frontal, parietal, and temporal cortices. It performs a critical function to ensure that select perceptions started in the cortex are integrated and become established in long-term memory. Squire states that the hippocampus and its related structures may serve as a device for forming conjunctions between ordinarily unrelated events that, once processed and represented by distinct sites in the hippocampus, bind together the relevant cortical sites that represent memory for a whole event.
Structures of the Medial Temporal Lobe System
The hippocampus is a well-delineated spiral brain structure, forming the medial margin of the cortex, and located on the medial wall of the lateral ventricle. Its appearance accounts for its name, meaning "seahorse." Another descriptive name is cornu ammonis (Ammon's horn). The hippocampus is the most plastic site in the brain. "Plastic" refers to morphological and physiological growth and change. This accounts for rapid acquisition (learning) of new information about facts and events that then can be available (memory) as conscious recollections. The storage role of the hippocampus is temporary in that memories are stored in the hippocampus for several months to 2 years. Once the relevant cortical sites are bound together, a memory may be retrieved without the use of the hippocampus. A series of studies has shown that memories that depend on the MTL gradually reorganize to be independent of it as time passed. This ensures that the MTL system will always be available for acquisition of new information.
Entorhinal, Perirhinal, and Parahippocampal Cortices
These are areas of cerebral cortex located mostly on the medial aspect of the temporal lobe, surrounding the hippocampus. The entorhinal cortex is the route through which almost all sensory information flows, from the cerebral cortex to hippocampus and from the hippocampus back to cerebral cortex. Two-thirds of the cortical input to entorhinal cortex comes from perirhinal and parahippocampal cortices. These also have reciprocal connections with widespread cortical structures and are involved in associative and emotional memory (Figs 3, 4).[11,12]
[Figures 3-4 ILLUSTRATION OMITTED]
MTL Memory Pathway
Information from throughout the brain comes into the corpus callosum from the cingulate gyrus. It enters the limbic system through the entorhinal cortex. This integrated information is multimodal: visual, auditory, sensory, and, to a lesser extent, kinesthetic. From the entorhinal cortex, it travels along the perforant pathway to the hippocampus. Within the hippocampus, learning occurs and memories are generated. The new signals are sent back to the entorhinal cortex, and from there to cortex (Figs 3, 4).
Pathways mentioned above may be disrupted by various pathologies. First, the pressure from the tumor on adjacent blood vessels causes a decrease in the blood supply to the area. This leads to hypoxia within the hippocampus and related structures, affecting memory function. Second, compression of the arterioles by the tumor causes venous congestion, eventually disrupting the blood-brain barrier, leading to local edema. This also restricts blood supply to sensitive structures, primarily hippocampus and the surrounding cortex. According to her daughter, Mrs. N had exhibited some subtle memory problems for a while, but these were thought to be due to age and stress at home. The dramatic memory loss that led her to be hospitalized could have resulted from a sudden exacerbation of one of the above mechanisms or both. Although a number of pathological events can produce such symptoms, tumors are used as an exemplar. A case study associating MTL amnesia with brain tumor follows.
Case Study: Mrs. N
Mrs. N remembers the years she spent teaching dance, managing a dance troupe, and choreographing recitals. She talks about the 30 years she worked at a local bank and recognizes some of her former patrons before they recognize her. But she can't remember driving herself home from church that Sunday in December when she was sick, and she can't remember the family Christmas she hosted the week before that. She doesn't remember her first hospitalization at all--the one when a magnetic resonance imaging (MRI) scan showed a mass in the medial portion of her left temporal lobe. She has very few memories of her second visit, a 5-day stay during which an anaplastic astrocytoma was removed. Mrs. N recovered quickly from surgery and returned to the neurosurgery clinic for a 3-week checkup. She easily carried on casual conversation with the office staff. Everyone there remarked on her progress. Her neurological exam was normal, and she negotiated the Mini Mental Status Exam (MMSE) effortlessly, that is, all of it except one item. When asked to name the three objects she had been told to remember at the start of the exam, she was unable to remember any. Still, she did the math calculations faster than the nurse-examiner. She talked easily about her diet, but seemed anxious when given a new schedule to taper her dexamethazone. She surprised everyone when a nurse who had visited her daily during her second hospitalization stopped in to see her, and she asked, "How did you know I was in the hospital?"
Understanding Mrs. N's Memory Problem
Mrs. N was brought to the hospital emergency department because of sudden transient global amnesia. She was admitted for follow-up, with memory loss her primary presenting symptom. A thorough neurological exam revealed the following abnormal findings:
* In an abbreviated mental status exam, Mrs. N could not name the president and could rename only two out of three objects after 5 minutes.
* An electroencephalogram (EEG) performed 2 days after admission showed left temporal lobe slowing in the range of theta rhythm mixed with delta rhythm, consistent with left temporal lobe dysfunction.
* An MRI performed 3 days after admission showed a 2.5- x 2-cm lesion touching the dura both at and below the left cavernous sinus within the MTL. There was such extensive edema within the left temporal lobe that it effaced most of the nearby sulci.
Memory problems can also result from the treatments patients undergo. Surgical resection of Mrs. N's anaplastic astrocytoma was accomplished by image-guided stereotactic microsurgery, a very accurate and gentle approach for brain tumor removal. Still, structures were probed and temporarily displaced. The tumor was resected back to normal-appearing white matter, with the most posterior extent of resection approximately 4 cm from the temporal tip. Thus, a small portion of the temporal lobe was removed in order to remove the tumor.
She has undergone 6 weeks of daily radiation therapy with a daily dose of 180 cGy to the primary tumor bed and also to a generous area surrounding it in the left temporal lobe site. Now that the radiation therapy is complete, Mrs. N has started chemotherapy.
Mrs. N still has retrograde amnesia for everything that happened 1 week prior to her hospitalization and surgery. She does not remember Christmas or hosting 21 relatives at her home. These memories are still absent 3 months later. She has complete anterograde amnesia for both of her hospitalizations and also for her surgery. Mrs. N's memory has gradually improved since her surgery. According to her husband's journal, "She started to get her memory back about the third day after surgery." However, partial anterograde amnesia persists.
Using Research to Develop Assessment Strategies
Knowledge of MTL structures and functions not only helps nurses understand patient symptoms but also provides a scientific basis for selecting tools for patient assessment. For instance, using distraction and delay can elicit important MTL memory deficits, as described above. A tool that incorporates distraction and delay in cognitive assessment is the MMSE. The recall item uses distraction to uncover problems with long-term memory. The patient is given three items to remember and is later asked to recall these same three items. Distraction occurs in the form of an intervening cognitive task. The MMSE assesses other aspects of short-term and long-term memory capacity in a variety of ways. As a well-established test for adults, it has many strengths including validity, reliability, and especially sensitivity; plus it is quick and easy to use. A baseline MMSE in the emergency department can help to quickly identify cognitive deficits, plus establish a reference point for future testing. The MMSE was useful in assessing and documenting Mrs. N's memory status throughout her recovery.
Another way to use distraction to assess MTL function is by telling a short story of one or two sentences while examining a patient. The story can use words that might engage the interest, arouse amusement, or convey a cultural overtone with which a patient can identify. For example,
A man had tickets to take his wife to see the Rockettes at Radio City Music Hall in New York. However, there was a transportation strike, and they could not get to the show.
The nurse continues conducting the exam and then asks the patient to repeat the story after a few minutes. Other memory tests using distraction are available, notably the Weschler Memory Test, but this is not easily used at the bedside and requires training to perform.
Especially important to this case, the non-matching to sample test incorporates the concept of delay to discern whether short-term or long-term memory is affected.[9,10] Using word tiles instead of objects may further reveal whether the problem involves verbal versus nonverbal learning or memory.
Persons with long-term memory problems tend to remember more items from the end of a list (recency) than from the beginning (primacy). Asking a patient to repeat a list of eight or more objects tests recency and primacy. Asking patients to recite digits forward and backwards might highlight problems, especially if the digit spans are lengthened. Lengthening digit spans tests memory capacity as well as the time it takes for memory to decay. A person who has no trouble doing "serial 7's" (short-term memory) might show deficits when asked to recite increasing lengths of digits.
It is critical to determine what is remembered and what is forgotten to individualize assessment methods and direction of care. Techniques include observation, listening, dialoging, purposeful questioning, and administering specific tests. Discrete information can be obtained by asking the patient, "What do you have trouble remembering?" and "What is easy to remember?" or "What did you have for breakfast?" Nurses can listen to conversations and detect what is remembered and what is forgotten--names, words, faces, objects, events, or places.
Is spatial learning intact? Observing patients in new and familiar places can assess spatial learning. How long does it take them to find their way in new surroundings? Do they become lost or disoriented in familiar places? Besides observation, objective assessment of spatial learning can be done with specific pen and pencil tests.
Procedural learning involves psychomotor skills. These can be assessed by observing the patient perform simple skills, including, in this case, crafts and dance.
Diaries are helpful tools, especially when kept by both the patient and the caregiver. Mrs. N, her husband, and her daughter each kept a diary and documented what Mrs. N could and could not remember. Data collected from these are shown in Table 2. Comparison of these data with Milner's data in Table 1 reveals that Mrs. N's problems are consistent with left MTL dysfunction.
Table 2 Things Mrs. N Can and Cannot Remember (Data from Patient and Family Diaries)
Things She Can Remember
Specific details of events immediately before the onset of memory loss.
The diagnosis and surgery discussion with her family and the the neurosurgeon.
Getting the fiducial markers placed on her head.
The faces of family, caregivers, bank customers.
Her way through the maze at the radiation therapy center.
Her safety deposit box number and security code at the bank.
Images of things she wants to talk about and how to draw them.
What she ate for lunch.
Her debit card number.
The location of her address book, etc.
Things She Cannot Remember
Married name of one of her dancers. (She remembered her maiden name.)
The fact that she would have chemotherapy after radiation therapy.
The first visit to the oncologist.
The neurosurgeon's name.
The word "tumor."
Words she wants to use while talking.
The restaurant's name where she ate.
New medical terms.
Once memory problems are detected and defined, nurses can develop problem-specific therapies. Mrs. N's long-term memory dysfunction resulted from her left MTL tumor. In developing nursing strategies for Mrs. N, the nurse can consider five concepts (Table 3). First, there is the need to support the affected memory system (verbal) in order to prevent discouragement and further decline. Second, because the right MTL associated with nonverbal memory is intact, therapies are designed to increase imaging and association, which compensate for left MTL losses. Third, procedural memory is also intact and is thus enhanced and encouraged. Because Mrs. N has used both areas of her brain (verbal and nonverbal), as a dancer, a bank cashier, and a crafter, these procedural memories are drawn upon and emphasized. Fourth, knowing that distraction and delay cause problems in left MTL loss, efforts are made to keep these at a minimum. Fifth, systematic serial memory testing is used to evaluate the effectiveness of therapy, detect overall improvement, and watch for decline.
Table 3 Therapies Based on MTL Research
Maintain and Support Existing Memory
Continue games, activities, and exercises the patient enjoys.
Give encouragement and explanations both for the patient and caregiver to prevent discouragement and withdrawal.
Supply needed words when asked or when problems are obvious.
Write commonly used names on a word list.
Establish a receptive environment in which the patient can ask for help.
Solve memory problems as they arise.
Encourage patients and caregivers to develop their own strategies based on current information.
Use the Intact Right Medial Temporal Lobe (Nonverbal)
Teach patients to associate the sound of a person's name with some visual feature of their body, such as "Norma has abnormal eyebrows." Start with only one or two essential names.
Teach using mental pictures and linking them with events. For instance, an appointment time might be at three o'clock. The patient can rhyme three with tree and think of a tree growing in the middle of the doctor's office.
Use both verbal and nonverbal cueing.
Use Procedural Memory
Develop and use other forms of memory, such as procedural memory.
Use rhythm (from dance), figures and calculations (from banking), and psychomotor skills (from crafts) to compensate for lost declarative memory function.
Reassure the patient and caregivers that intelligence and prior skills are retained.
Compensate for Problems and Distraction
Encourage keeping a journal, writing down things immediately, using check-off lists.
Write instructions down for the patient and for caregivers.
Place a notice (sticker) of memory problem on the chart.
Teach the patient to record information, rather than relying on memory, using the simplest-to-use device possible for recording.
Teach chunking and encourage rehearsing.
Keep instructions short. Give important points first or last--not in the middle of conversation.
Control the environment. Decrease physical distractions, such as noise, pain, fatigue, and stress.
Teach patients routines that minimize their chances of forgetting. For instance, "Always put your key on the hook by the door; nowhere else."
Memory Is a Physical, Neurological Entity
Teach patients, clinicians and caregivers to use memory to keep track of improvements or decline in the overall health of the individual with a left temporal lobe lesion.
Maintain nutrition, exercise, health.
Mrs. N performed consistently well on all areas of the MMSE except in recall (Fig 5). After an initial decline 3 weeks postoperatively, she has shown continuing improvement. Recently, a worsening is evident in her copying an image that she has copied many times before. Further testing will determine whether this is deterioration of function or a temporary event associated with factors such as response to radiation or fatigue. Her latest MRI results show complete absence of tumor. Finally, Mrs. N has developed her own personal strategies for coping with her memory problems, and these are listed in Table 4.
[Figure 5 ILLUSTRATION OMITTED]
Table 4 Mrs. N's Personal Coping Mechanisms (Data From Her Diary and From Interviews)
"I associate things in my mind."
"I think everything is tied (memory, energy, appetite)."
"When I talk, I sometimes have problems and ask people to wait a few seconds."
"I do try and think about everything at different times."
"I ask whoever is there to think of the word."
"I do try and use my memory when talking, to finish each sentence."
"My granddaughter's name was gone, so I had her write it on the blackboard."
"Things that interfere: nausea, fatigue, the hollow sound in my ear from radiation therapy."
Daughter: "We are trying to stimulate her mind by teaching her new card games, board games, and a different domino game. She quickly picks up the new games and really enjoys them. It's good to see her laugh."
Research on the MTL memory system has yielded much information that can help nurses plan effective assessment and therapy strategies for their patients with MTL amnesia. Patients and caregivers contribute their ideas and experiences as they work together to find ways of coping with and compensating for partial memory loss.
So far, Mrs. N continues to progress in her daily battle with a malignant brain tumor. However, the tumor itself and the medical therapy to fight it have significantly affected her memory. Losing memory, even partially, affects every aspect of life. Memories allow us to relate to the world and to stay independent. Therefore, nursing care for Mrs. N includes more than administering pills for nausea and protein supplements for persistent anorexia. It includes therapy for her memory to maintain the abilities she has and to enable her to continue her role as an active participant in life.
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[10.] Squire LR, Zola SM: Ischemic brain damage and memory impairment: A comment. Hippocampus 1996; 6: 546-552.
[11.] Squire LR, Zola-Morgan S: The medial temporal lobe memory system. Science 1991; 253: 1380-1386.
[12.] Squire LR, Zola-Morgan S: Structure and function of declarative and nondeclarative memory systems. Proc Nat Acad Sci 1996; 93: 133515.
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Questions or comments about this article may be directed to: Gail A. Burleson, MS RN CNRN, Mott Community College, 1401 E. Court Street, Flint, MI 48503. She is an Instructor of Nursing, Division of Health Sciences.
Barbara Therrien, PhD RN FAAN, is Director of the Center for Enhancement & Restoration of Cognitive Function at the University of Michigan School of Nursing.
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|Author:||Burleson, Gail A.; Therrien, Barbara|
|Publication:||Journal of Neuroscience Nursing|
|Date:||Apr 1, 2000|
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