Memory dysfunction after brain traumatic injury depends on the Marshall score but not on the duration of sedation: preliminary findings

Introduction

The aim of the study was to identify the causes of memory dysfunction after brain traumatic injury. Recently, a light anaesthesia, more than a deep anaesthesia, has been accused of causing postoperative cognitive dysfunction [1]. Conversely, the daily sedative interruption in ICU patients does not result in adverse mental outcome [2]. Patients affected by brain injury can have severe memory dysfunction after discharge [3].

Methods

One hundred and twenty-one patients were admitted to an emergency department ICU in 2007 with major trauma (injury severity score >15) and severe to moderate brain injury (Glasgow coma scale <13). Of these patients, 25 died in the days following trauma. Thirty-four of them – submitted, during the ICU stay, to several lengths of sedation (17.2 ± 9.2 days; range 1 to 40) – were evaluated at the follow-up visit 6 months after discharge from the ICU. As a part of neurological evaluation, verbal and visuospatial memory tests were administered to the patients to obtain a diagnosis of memory dysfunction. During the ICU stay, from the ICU database (FileMaker Pro 5.5v2; FileMaker, Inc., Santa Clara, CA, USA) with authorization of the Careggi Teaching Hospital Committee of the Emergency Department, the following parameters were collected for every patient: age, sex, abbreviated injury scale, injury severity score, Simplified Acute Physiology Score II, in the field Glasgow coma scale, Marshall score, worst values of lactates and ScvO₂ within 24 hours from trauma, length of sedation and ICU stay. The median of each collected parameter in the group of patients was used as the cutoff value to divide them into two categories: risk factor for memory dysfunction present or absent. A two-by-two analysis was carried out and Fisher's exact test was used for comparisons. P < 0.05 was considered significant.

Results

Memory dysfunction was observed in 15 out of 34 patients. Only Marshall score >2 (8/15 vs. 3/19; P < 0.05) represented a significant risk factor for memory dysfunction.

Conclusion

In brain traumatic injury patients the extent of brain damage, qualified by the Marshall score, is related to late memory dysfunction regardless of the length of sedation and the severity of the initial clinical picture.