AMNESIA FOLLOWING SEVERE HEAD INJURY*
G. SISLER, M.D.! H. PENNER, M.D. 2
This report concerns some aspects of the problem of establishing valid and reliable criteria for post-traumatic amnesia, and of relating this to other cognitive functions in the post-injury period. Of specific interest are the variability of the duration of retrograde and anterograde amnesia on attempts at repeated assessment, and the relationship between the time of return of full orientation and the end of the period of anterograde amnesia. A prospective study was undertaken of sixty consecutive patients who had suffered severe head injuries and had been admitted to the neurosurgical service of the Winnipeg General Hospital. The object of this study was to obtain information regarding organic, psychological and social indices of the future clinical course. In 1932 Ritchie Russell (6) first identified one such index, "The duration of post-traumatic amnesia", which he found to be positively correlated with the severity and duration of subsequent disability, and others have similarly reported (1-5, 7). In considering the literature and in attempting to apply this criterion, a number of problems became evident which limit the specificity of a statement such as - "Posttraumatic amnesia lasted three days." *
This study was supported by National Public Health Research Grant #606-7-205. Manuscript received JUly1974. I ,2.Department of Psychiatry, University of Manitoba and the Health Sciences Centre, Winnipeg, Manitoba.
Can. Psychiatr. Assoc. J. Vol. 20 (1975)
These are: • 'Post-traumatic amnesia' may refer to retrograde and anterograde amnesia, or only to the latter. • Russell originally defined posttraumatic amnesia as the period during which the patient is unable to store current events. However, he and others use this term interchangeably with such other poorly-defined concepts as period of 'coma', of 'impaired consciousness', or of 'delirium' . • In reported studies the criteria for determining the beginning and end of the period of amnesia and the manner and time of posing the relevant questions and tests are not specified. Such terms as 'islands of memory' and 'beginning of continuous memory' are used without taking into account that in assessing the influence of the injury, an attempt is made at some often unspecified later date to compare memory function following the accident with what one assumes it would have been otherwise. This poses many difficulties - what memories is a person expected to have of a particular period after a week or a month? Method These sixty severely head-injured patients were selected by applying an arbitrary but specific definition of depth and duration of coma - all patients who within 24 hours of injury had not regained consciousness to the point that they
333
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CANADIAN PSYCHIATRIC ASSOCIATION JOURNAL
responded with intelligible words or carried out two of three simple commands: "close (or open) your eyes, close (or open) your mouth, move a specified limb". All patients had blunt force injuries because none with a focal missile-type wound had a period of coma sufficiently prolonged to meet the criteria. Originally it had been planned to record from daily assessments the time of emergence from 'coma' or 'unconsciousness', and from "confusian or delirium', and thus the time of return to 'full consciousness' or 'full orientation', but it was soon evident that such terms lack agreed definition, and that in a given case the change was a gradual process comprising the return, in various sequences and at times with subsequent relapse, of several functions and abilities. It became necessary to assess daily each function, since the end of the coma or delirium could only be determined after the data had been accumulated, and by an arbitrary definition of the criteria of such end points. During the initial hospital stay the psychiatrist recorded daily assessments of the level of consciousness and of various cognitive functions. His direct observations were coded separately from information in the nurses' notes entered during the previous 24-hour period. Daily record was kept as to whether the patient responded to voice in any way, responded with intelligible words, and could give correctly his name, the year, month, day, date and place. Using specific criteria the degree of spontaneous movement in response to pain, alertness, mood and the presence of hallucinations or delusions were recorded. Expressive dysphasia was assessed by testing the ability to name two common objects, and short-term memory by the ability to retain these names for three minutes. Receptive dysphasia was tested by the ability to carry out two of three simple commands. Following discharge an attempt was made to reassess each patient regularly, the frequency and time depending on the clinical state at discharge and other factors such as his availability and cooperation. From the time the patient regained the ability to speak or write repeated attempts were made to identify valid pre-accident and postaccident memories, and thus to circumscribe the periods of retrograde and of anterograde amnesia.
Results Tables I and II indicate for retrograde and anterograde amnesia respectively the varia-
TABLE
I
24 P ATlENTS
VARIA TlON OF RETROGRADE AMNESIA -
(for explanation see text) Examples
No. of patients
5
G. SISLER, M.D.! H. PENNER, M.D. 2
This report concerns some aspects of the problem of establishing valid and reliable criteria for post-traumatic amnesia, and of relating this to other cognitive functions in the post-injury period. Of specific interest are the variability of the duration of retrograde and anterograde amnesia on attempts at repeated assessment, and the relationship between the time of return of full orientation and the end of the period of anterograde amnesia. A prospective study was undertaken of sixty consecutive patients who had suffered severe head injuries and had been admitted to the neurosurgical service of the Winnipeg General Hospital. The object of this study was to obtain information regarding organic, psychological and social indices of the future clinical course. In 1932 Ritchie Russell (6) first identified one such index, "The duration of post-traumatic amnesia", which he found to be positively correlated with the severity and duration of subsequent disability, and others have similarly reported (1-5, 7). In considering the literature and in attempting to apply this criterion, a number of problems became evident which limit the specificity of a statement such as - "Posttraumatic amnesia lasted three days." *
This study was supported by National Public Health Research Grant #606-7-205. Manuscript received JUly1974. I ,2.Department of Psychiatry, University of Manitoba and the Health Sciences Centre, Winnipeg, Manitoba.
Can. Psychiatr. Assoc. J. Vol. 20 (1975)
These are: • 'Post-traumatic amnesia' may refer to retrograde and anterograde amnesia, or only to the latter. • Russell originally defined posttraumatic amnesia as the period during which the patient is unable to store current events. However, he and others use this term interchangeably with such other poorly-defined concepts as period of 'coma', of 'impaired consciousness', or of 'delirium' . • In reported studies the criteria for determining the beginning and end of the period of amnesia and the manner and time of posing the relevant questions and tests are not specified. Such terms as 'islands of memory' and 'beginning of continuous memory' are used without taking into account that in assessing the influence of the injury, an attempt is made at some often unspecified later date to compare memory function following the accident with what one assumes it would have been otherwise. This poses many difficulties - what memories is a person expected to have of a particular period after a week or a month? Method These sixty severely head-injured patients were selected by applying an arbitrary but specific definition of depth and duration of coma - all patients who within 24 hours of injury had not regained consciousness to the point that they
333
334
Vol. 20, No.5
CANADIAN PSYCHIATRIC ASSOCIATION JOURNAL
responded with intelligible words or carried out two of three simple commands: "close (or open) your eyes, close (or open) your mouth, move a specified limb". All patients had blunt force injuries because none with a focal missile-type wound had a period of coma sufficiently prolonged to meet the criteria. Originally it had been planned to record from daily assessments the time of emergence from 'coma' or 'unconsciousness', and from "confusian or delirium', and thus the time of return to 'full consciousness' or 'full orientation', but it was soon evident that such terms lack agreed definition, and that in a given case the change was a gradual process comprising the return, in various sequences and at times with subsequent relapse, of several functions and abilities. It became necessary to assess daily each function, since the end of the coma or delirium could only be determined after the data had been accumulated, and by an arbitrary definition of the criteria of such end points. During the initial hospital stay the psychiatrist recorded daily assessments of the level of consciousness and of various cognitive functions. His direct observations were coded separately from information in the nurses' notes entered during the previous 24-hour period. Daily record was kept as to whether the patient responded to voice in any way, responded with intelligible words, and could give correctly his name, the year, month, day, date and place. Using specific criteria the degree of spontaneous movement in response to pain, alertness, mood and the presence of hallucinations or delusions were recorded. Expressive dysphasia was assessed by testing the ability to name two common objects, and short-term memory by the ability to retain these names for three minutes. Receptive dysphasia was tested by the ability to carry out two of three simple commands. Following discharge an attempt was made to reassess each patient regularly, the frequency and time depending on the clinical state at discharge and other factors such as his availability and cooperation. From the time the patient regained the ability to speak or write repeated attempts were made to identify valid pre-accident and postaccident memories, and thus to circumscribe the periods of retrograde and of anterograde amnesia.
Results Tables I and II indicate for retrograde and anterograde amnesia respectively the varia-
TABLE
I
24 P ATlENTS
VARIA TlON OF RETROGRADE AMNESIA -
(for explanation see text) Examples
No. of patients
5
