Journal of Traumatic Stress, VoL 9, No. 3, 1996

Brief Report

Posttraumatic Stress Disorder, Flashbacks, and Pseudomemories in Closed Head Injury

Richard A. Bryant'

Posttraumatic stress disorder (PTSD) is rarefy diagnosed in patients with significant head injuq This paper reviews two patients who were amnesic for events surrounding their motor vehicle accidents ( W A S ) but developed delayed-onset PTSD. Symptoms included vivid images of the W A S that were based on information learnt following the trauma. These cases indicate that amnesic head injured patients can suffer pseudomemories that are phenomenologically similar to flashbacks observed in PTSD. Implications for understanding the nature of flashbacks are discussed KEY WORDS: posttraumatic stress; motor vehicle accidents; traumatic brain injury; flashbacks; pseudomemories.

Posttraumatic stress disorder (PTSD) is rarely diagnosed in patients with head injuries who do not recall their trauma. One study that investi- gated this issue reported that none of their head injured patients satisfied criteria for PTSD (Middleboe, Andersen, Birket-Smith, & Friis, 1992). It is often assumed that patients who do not consciously recall their trauma will not suffer intrusive symptoms, and consequently will not satisfy DSM- IV criteria for PTSD (American Psychiatric Association [MA], 1994). Ac- cordingly, little attention has been given to the manner that head injured patients reexperience aspects of their trauma. The lack of investigation into posttraumatic intrusive symptoms of head injured patients is surprising con- sidering that many people are traumatized through accidents each year, and a significant proportion of these patients sustain head injuries (Bull, 1979). Despite the increasing research being devoted to post-accident stress responses (Brom, Kleber, & Hofman, 1993; Hickling & Blanchard, 1992),

'School of Psychology, University of New South Mles, NSW, 2052, Sydney, Australia.

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this work has largely neglected responses of head-injured patients (cf. Malt, 1988; Middleboe et al., 1992).

There is evidence, however, that head injured patients do experience posttraumatic intrusive symptoms. Several case studies have described head injured patients with PTSD (Horton, 1993; MacMillan, 1991). Further, al- though head injured patients display less intrusive symptomatology than non-head injured patients following a traumatic accident, amnesic patients do nonetheless display intrusive symptomatology (Bryant & Harvey, 1995). The rationale to investigate posttraumatic intrusive symptomatology in head injured patients is further indicated by findings that posttraumatic anxiety and organic mental dysfunction are associated in 75% of postacci- dent cases (Malt, 1988), and with theoretical proposals that PTSD is me- diated by neurophysiological mechanisms (Watson, Hoffman, & Wilson, 1988).

Different theoretical frameworks may be employed to conceptualize intrusive symptoms in head injured patients. Cognitive theories of PTSD propose that following a trauma, PTSD patients develop cognitive repre- sentations of the traumatic event that are established within a fear network (Litz & Keane, 1989). These representations are activated by trauma-re- lated stimuli that trigger the fear network and result in the experience of distressing and intrusive memories. On the basis of such a model, it may be argued that patients who do not recall their trauma are less likely to experience intrusive thoughts about the trauma because there is no con- scious cognitive representation of the event. It could also be argued that head injured patients who suffer amnesia for events surrounding their trauma may implicitly process information in a way that is not consciously recalled. Recent work has demonstrated that multiple memory systems may mediate the encoding and retrieval of information on explicit and implicit levels (Roediger, 1990). Further, there is evidence that implicit and explicit memory systems function independently in individuals with brain dysfunc- tion (Schacter, 1992). Specifically relevant to the issue of intrusive images in head injured patients is the proposal that perceptual and semantic rep- resentations can operate independently (Schacter, 1990). Accordingly, it may be argued that head injured patients may encode aspects of traumatic events that are not consciously recalled. Consistent with this notion, Horton (1993) has noted that dual memory systems that involve declarative and nondeclarative memory may be critical in PTSD following head injury.

The aim of this paper is to present two case studies of head injured patients who reported intrusive imagery, and satisfied criteria for PTSD diagnosis, despite being amnesic for events surrounding their trauma. The focus of this paper is to (a) highlight that amnesic head injured patients can suffer posttraumatic intrusive symptoms, and (b) indicate that the study

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of amnesic patients with intrusive imagery can provide a useful means to investigate the nature and course of flashbacks in PTSD patients.

Case 1

BS was 27 years old when he was involved in a motor vehicle accident in which he sustained a severed aorta, multiple broken ribs, a collapsed lung, and a severe head injury. Police reports indicated that BS was.driving his car alone when another vehicle crossed the road at high speed and collided with BS’s car. BS reported that the last thing he recalled prior to losing consciousness was the day before the MVA. The first thing he re- membered after the MVA was waking in hospital. His length of posttrau- matic amnesia was 5 weeks. BS reported that he had no awareness of the MVA apart from police reports and a newspaper photograph of his wrecked car. A computerized tomography (CT) scan indicated right frontal and tem- poral lobe contusions, and right fronto-parietal scalp haematoma. Neuro- psychological testing indicated deficits in verbal memory, reading skills, and organizational planning. Following five months of hospitalization, BS was transferred to a rehabilitation unit. BS showed no signs of overt emotional disturbance following his injury.

Ten months after the injury, BS commenced training to drive again. BS reported that 2 days prior to his third driving lesson he was travelling as a passenger with his wife when a car narrowly missed hitting their car. He admitted that he was worried by this incident but that his concern di- minished soon after the event. On his third driving lesson, BS experienced a sudden dissociative experience. When he was instructed to start the car, he suddenly became rigid, stared straight ahead of him, and was sub- sequently unresponsive to all verbal instructions. BS remained in this state for approximately 2 hr and was transferred by ambulance to a local hospital. On arriving at the hospital, BS reportedly became aware and responsive, and discharged himself. That night BS experienced an involuntary image of the MVA in which he imaged the wreck of his car and saw himself bleeding in the front seat. He subsequently reported similar imagery oc- curring several times a day. These intrusions predominantly involved vivid imagery of the wrecked car and of BS lying bleeding in it. These images were stationav and he described them as being similar to the newspaper photograph of his car. BS also reported nightmares in which he experienced being in his car as it collided with the oncoming car. BS reported that he was unable to avoid these images, and that they were associated with ex- treme anxiety. BS reported that his anxiety was closely associated with his concerns about his children’s safety if he drove again. BS was not using

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any prescribed or other drugs at the time of the imagery. One month after the initial intrusion, BS’s intrusions changed in that he reported that he began to see his children lying dead in the wrecked car. BS responded to this anxiety and intrusive symptoms with pervasive avoidance behavior. This included avoidance of driving, even as a passenger, social withdrawal, and avoidance of discussions of his MVA. BS also demonstrated significant lev- els of autonomic arousal, including heightened startle response, hy- pervigilence, and insomnia. BS satisfied DSM-IV criteria for F’TSD with delayed onset. On the Impact of Event Scale (IES: Horowitz, Wilner, & Alvarez, 1979) (scored 0,1,3,5) BS scored 56, with 31 on the Intrusion scale and 25 on the Avoidance scale. These scores reflect significant levels of posttraumatic stress. BS did not evaluate his imagery as an accurate mem- ory of what had occurred. He maintained that he was amnesic of the ac- cident and that the imagery was a result of concerns he felt about the accident.

Case 2

RM was 23 years old when he was involved in a MVA. He sustained multiple injuries, including broken ribs, severe whiplash, and a closed head injury. A scan indicated an extensive subdural hematoma in the frontal lobes. Neuropsychological assessment indicated that he sustained significant deficits in verbal and visual memory, planning skills, and focused attention. RM was hospitalized for 2 months and subsequently admitted to a reha- bilitation unit for a further 2 months. Initial police reports indicated that RM was driving the vehicle because neither of the two passengers in the car with him held driving licenses. The female passenger who was report- edly seated next to him was killed and the passenger in the rear seat was paralyzed as a result of the accident. There were no eyewitnesses to the MVA. It was originally concluded that RM lost control of the car and ran into a pole at high speed. RM’s last recollection before the MVA was leav- ing a nightclub with his two friends and him arguing with the woman who was killed in the MVA because she claimed that she was sober enough to drive. He reported that he did not initially understand how he came to be driving the car when it crashed. His first recall after the MVA was waking in hospital. His period of posttraumatic amnesia was 3 weeks.

Seventeen months after the MVA, RM reported that he began to have intrusive imagery related to the MVA. RM was not using any prescribed or other drugs at the time of the imagery. The onset of the intrusions was preceded by police reports that the position of the dead person’s clothing and jewelry indicated that she was driving at the time of the MVA. An-

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nouncement of this report apparently resulted in intense community hos- tility towards RM for allowing her to drive and in a significant rise in R M s anxiety levels. RM reported that one night he was lying in bed when he experienced his initial intrusion. He reported that he pictured himself in the passenger seat in the car and he saw the woman being thrown against the steering wheel, then hitting RM, and being thrown out the back of the car. Immediately afterwards, RM saw himself being thrown against the steering wheel and feeling his head hit the dashboard. RM described this scene in vivid detail and reported that he experienced extreme anxiety fol- lowing the imagery. He described the intrusion in terms of a reexperiencing of the event rather than a recollection. RM continued to experience this intrusion several times a day for two months. After the onset of the intru- sions, RM reported heightened anxiety, avoidance behavior towards road- related events and topics of conversations, and exaggerated startle response. That is, he satisfied diagnostic criteria for PTSD. On the Impact of Event Scale, RM scored 51, with 28 on the Intrusion scale and 23 on the Avoidance scale. These scores reflect significant levels of posttraumatic stress. RM maintained that he was amnesic for events surrounding his ac- cident, and attributed his intrusive imagery to “bits of memories that must have been registered but were forgotten for a while”. RM reported that he believed that his imagery reflected his recall of the event.

Discussion

These two case studies indicate that traumatically brain injured pa- tients who do not recall episodic features of their trauma can experience intrusive cognitions in a manner that is phenomenologically similar to PTSD flashbacks in non-head injured patients. Although these patients’ head injuries indicated that they had no conscious recall of the traumatic events, their intrusions appear to satisfy criteria described by DSM-IV. Fur- ther, their associated anxiety and subsequent avoidance behavior is consis- tent with the experience of a PTSD flashback. These reports highlight that head injured patients are susceptible to intrusive cognitions of their trauma.

The nature of intrusive imagery in amnesic patients raises several in- teresting points concerning posttraumatic cognitions generally. Posttrau- matic imagery appears to comprise a complex array of cognitive images. Horowitz (1983) has described the variable nature of imagery in terms of vividness, subjective and objective localization, and sense of reality. Dis- tinction is also made between images that are formed in different contexts. Posttraumatic imagery in head injured patients indicates that more detailed attention needs to be given to the definition of intrusive cognitions in

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PTSD. There is a need to distinguish between involuntary recollections of a recalled event, pseudomemories of events that are not recalled, and-im- agery that involves a sense of reexperiencing an event. Appropriate defi- nition of the different types of imagery experiences is important for both clinical diagnosis of PTSD and theoretical understanding of the complexity of cognitive responses to trauma.

Network models of PTSD infer that flashbacks have their origin in cognitive representations formed at the time of the traumatic event (Litz & Keane, 1989). The current case studies suggest that representations of the traumatic event may be subjectively generated subsequent to the origi- nal trauma. It would seem that cognitive models may need to recognize that traumatized individuals can develop representations of a traumatic event at some time after their trauma, and that these representations can be experienced as involuntary and subjectively compelling. Alternately, these case studies may be interpreted in terms of implicit processing of the traumatic event. It may be argued that these patients encoded the traumatic events at a nondeclarative level, and subsequently recalled the events in an unintentional manner and in the absence of conscious recall (Schacter, 1992). It is plausible that these patients suffered impaired consciousness at the time of impact, and accordingly were able to implicitly encode events. It is impossible to determine the likelihood of this occurrence in a case study design, however the issue of implicit learning of traumatic events dur- ing impaired consciousness is consistent with recent developments in cog- nitive psychology and deserves more rigorous investigation.

These cases also highlight that intrusive posttraumatic imagery need not reflect historical truth as much as personally meaningful attributions about a significant event. In both cases it can be said that the patients developed pseudomemories that were congruent with their emotional needs and individual interpretations of events. BS’s intrusions were congruent with his fears of harm to himself and his family. It is significant that his imagery altered across time in association with his changing concerns. That is, as he developed increasing concern that his children would die if he drove again, there was an extension of the pseudomemory in which he visu- alized his children dead in the wrecked car. It can be argued that these pseudomemories were perceptions of traumatic events that were recon- structed on the basis of (a) information available to the patient, and (b) emotional state of the patient. That is, the pseudomemories that were re- constructed were congruent with the primary emotional state of the patient. It also needs to be recognized that the stage at which the patient perceives the trauma as being threatening may influence the posttraumatic response. Malt and Olafsen (1992) reported that patients who evaluated their trauma as threatening late in the course of adjustment were more likely to display

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personal difficulties. Accordingly, head injured patients who develop aware- ness of their trauma and its consequences late in their recovery process may experience posttraumatic difficulties associated with this delayed evalu- ation.

The possibility that intrusive imagery may not reflect historical truth suggests that caution is required when interpreting posttraumatic memories within clinical and forensic contexts. People judge the accuracy of their autobiographical memory largely on the basis of perceptual and contextual details (Johnson, Foley, Suengas, & Raye, 1988). Further, people’s belief in the accuracy of a memory tends to increase with rehearsal (Johnson, 1988). Flashbacks typically involve vivid detail and occur repeatedly, and consequently are perceived by individuals as accurate recollections of a traumatic event. Accordingly, reports of flashbacks should not necessarily be considered historically accurate (Frankel, 1994). Even non-head injured traumatized individuals modify their recall of their trauma across time (Schwarz, Kowalski, & McNally, 1993). Further research is needed with both head injured and non-head injured patients that investigates the ac- curacy and consistency of intrusive cognitions.

These case studies also suggest that head injury may be associated with specific types of posttraumatic intrusions. For example, frontal lobe pathol- ogy has been associated with spontaneous confabulations (Kopelman, 1987) and Capgras syndrome (Fleminger & Bums, 1993). It is possible that the organic dysfunction following brain injury may contribute to intrusive cog- nitions in head injured patients. This possibility deserves consideration be- cause most head injuries sustained in motor vehicle accidents involve frontal lobe damage. The possible association between brain injury and in- trusive cognitions is also indicated by reports that memory dysfunction fol- lowing closed head injury is associated with increased subjective complaints, including anxiety (Jurado, 1993). It is also conceivable that personality fac- tors may influence the development of intrusive cognitions (Horowitz, 1983), and these predisposing individual differences may interact with brain dysfunction in the posttraumatic phase. The convergence of intrusive symp- toms following brain injury and PTSD highlights that careful diagnosis is needed because a range of PTSD symptoms (e.g., anxiety, insomnia, con- centration deficits) are common sequelae of closed head injury (Levin & Grossman, 1978).

The capacity of head injured patients to experience intrusive imagery of a traumatic event suggests that investigation of these patients may be useful in extending our understanding of intrusive cognitions generally. Re- search on flashbacks in non-head-injured patients is restricted by these sub- jects’ awareness of the traumatic event, which limits the researcher in manipulating this critical variable. In the case of one who is amnesic for

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events surrounding the trauma, however, the researcher can control the information available to a patient, monitor attributions that are made on the basis of available information, and index the relationship between emo- tional state and available information in the development of the pseudomemory. For example, recent work that has employed self-discrep- ancy theory to investigate autobiographical memory and anxiety may be usefully adapted to the study of flashbacks in PTSD (Strauman, 1992). De- velopment of paradigms that investigate intrusive cognitions in head injured and non-head injured traumatized individuals could provide a fullef under- standing of the role of posttraumatic imagery in trauma response.

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