Memory recovery after traumatic coma

Abstract

Serial memory testings of 108 head injury cases were studied over a two year follow up period. The length of the post-traumatic disorientation period (PTD) was found to be an important factor in the rate of memory recovery. In the first year after injury marked differences were seen in the recovery rates of all four PTD groups, the three short PTD groups (less than one month) finally yielding from 74% to 92% cases (according to the group) with normal memory function, while the long PTD group (more than one month) only produced 45% cases (statistical significance 0.05). During the second year and up to the end of this survey relatively little change in memory status occurred in any of the cases, regardless of their PTD. Any improvement that did occur was at an extremely slow rate. Brain damage was the main cause of memory defect in the long PTD group, while anxiety symptoms had a more important role in the short PTD cases. The shapes of memory recall curves were analysed in recovering patients. Three types of curve were found. The incidence of the shape of the curve also varied according to the PTD time (statistical significance 0.05) between long and short PTD groups. Curve shapes are discussed in terms of memory mechanisms, and a possible prognostic value is suggested. Analysis of test errors indicated not only a defective transfer of material from short term long term memory storage but also in some cases, a more complex mechanism involving inappropriate fixation of attention. Reverberation of memory traces is suggested as being a possible cause of interference in both short and long term memory mechanisms. A marked difference in recall performance between auditory and visual presentation of word lists was found to be a useful lateralising sign.

Predictions of recall and study strategy decisions after diffuse brain injury

“…The first four items were studied, but excluded from data analysis to control for primacy effects [53,54]. The 36 remaining pairs were divided into two blocks of 18.…”

The effects of minor closed head injury upon human memory: Further evidence on the role of mental imagery

“…Nevertheless, these cases probably account for less than 10% of all hospital admissions following head injury. Patients with minor head injuries may also complain of an impaired ability to remember, even after the return of normal awareness and orientation (Lidvall, Linderoth, & Norlin, 1974), and these subjective reports can often be confirmed by means of objective psychometric testing (Conkey, 1938;Parker & Serrats, 1976). It is now generally agreed that even a minor closed head injury may give rise to a persistent disturbance of memory function.…”

Methodological Issues in Longitudinal Research on Cognitive Recovery after Traumatic Brain Injury: Evidence from a Systematic Review

“…Overall, there was a wide fluctuation in the timing of assessments. Most assessments occurred in the first 12 months after injury; only three studies completed assessments in the interval between the first and second years post-trauma (Eker, Hagstadius, Linden, Schalen, & Nordstrom, 2001; Parker & Serrats, 1976; Van Zomeren & Deelman, 1978). The largest number of assessments in a single study was seven in the first 2 years (Parker & Serrats, 1976); most other studies ( n = 11) used at least four assessment time-points.…”