REHABILITATION OF MODERATE TO SEVERE TBI: COMA: POSTTRAUMATIC AMNESIA (PTA)

  • Occurrence: Occurs in all patients when they emerge from coma

  • Definition: Disorientation to time, place, and person; a confusional state; diminished memory; and reduced ability to attend and respond to environmental cues

  • Cognitive characteristics: For example, a deficit in initial learning usually occurs in injuries to diencephalic structures, and an increased rate of forgetting new information in injuries to the temporal lobes. The cognitive characteristics have clinical significance

  • Behavioral characteristics: Agitation is the most common and significant behavioral change and should be addressed by:

    • A comprehensive examination that emphasizes potential sources of agitation, such as fractures, peripheral nerve injuries, skin lesions, seizures, CNS infection, current medications, and other cardiopulmonary, endocrine, hepatic, renal, and metabolic sources

    • The Agitated Behavior Scale, one-to-one monitoring, and behavioral modification

    • Physical restraints and environmental changes

    • Medications, particularly for shorter lengths of stay, that do not cause sedation or secondary brain damage, interfere with cognitive recovery or long-term outcomes, or have significant side effects
      • Stimulating agents, such as amantadine or methylphenidate
      • Antidepressants, such as amitriptyline or trazodone
      • Agents that reduce excitatory or augment inhibitory effects, such as beta blockers, lithium, carbamazepine, and buspirone
      • Sedatives, such as lorazepam, in periods of extreme agitation

    • Monitoring of cognitive recovery, which may precede recovery from agitation, with the:
      • Galveston Orientation and Amnesia Test (GOAT), which assesses temporal orientation primarily and is recommended in the acute care setting
      • Orientation Group Monitoring System, which is more sensitive in detecting medical complications than GOAT and is recommended in the rehabilitation setting
      • Three-word recall, which is simpler to administer and more reliable than GOAT, when the GOAT contains materials the patient knew prior to injury, which obscures GOAT's ability to determine recovery of continuous memory (Schwartz, et al 1998)

  • Duration: Duration can reliably and quickly be assessed by the Galveston Orientation and Amnesia Test (GOAT), which should be administered daily. PTA duration has clinical significance and prognostic implications

  • Other characteristics:
    • Rarely complete - For example, patients can achieve some long-term learning of tasks that require limited attention, are frequently repeated, and/or involve the acquisition of motor skills
    • Accompanied by retrograde amnesia - the inability to remember information acquired prior to the injury - but PTA usually lasts longer than retrograde amnesia. In retrograde amnesia, information acquired close before the injury is less likely to be recalled than information acquired earlier. With progress, the duration of retrograde amnesia is reduced from years (in some cases) to about 30 minutes

Based on information in Medical Rehabilitation of Traumatic Brain Injury, L.J. Horn and N.D. Zasler, eds. St. Louis, MO, Mosby, 1996, except for information where other papers are cited.