Original articleLong-term sleep disturbances in adolescents after minor head injury
Introduction
Head injuries are frequent events among children and adolescents. In the United States, approximately 100,000 children are hospitalized every year because of head injury [1]. Minor head injury (MHI) is characterized as a brain concussion that can cause a transient loss or impairment of consciousness (for less than 30 minutes), vomiting, and a short anterograde or retrograde amnesia. In MHI the Glasgow Coma Scale (GCS) score is 13 or higher [2]. Neurologic evaluation, including computed tomography (CT) and magnetic resonance imaging (MRI) scans, electroencephalogram (EEG), brainstem auditory-evoked responses, electronystagmograms, and audiograms, is normal or reveals minor, transient abnormalities [2]. However, although considered a “benign” event, MHI may have long-term effects generally termed postconcussive syndrome, or, in less-frequent cases, may result in posttraumatic stress disorder (PTSD).
Postconcussive syndrome includes headaches, memory and concentration impairments, anxiety, mood disorders, and sleep disorders [2]. There is some overlap with symptoms found in the PTSD, which is a mental disorder consisting of flashbacks, nightmares, and an inability to cope with daily life events. The syndrome primarily affects adults and includes two types of sleep disturbances as part of the diagnostic criteria (based on the DSM-IV): re-experiencing events (nightmares, Criteria B) and a hyperarousal state (difficulty initiating and maintaining sleep, Criteria D). There is controversy as to whether MHI can cause PTSD because of the loss of consciousness and the posttraumatic amnesia, which occur in the event [3].
Adolescents and young adults who have undergone MHI may suffer from sleep disorders without necessarily having other symptoms of the postconcussive syndrome or PTSD. Subjective evaluation of individuals after MHI revealed complaints of difficulties in initiating and maintaining sleep, early morning awakenings, decreased daytime performance, and a generally decreased sleep quality [4], [5]. Adult PTSD patients also complained of nightmares, but these did not necessarily exist in children with PTSD [6]. Few studies have attempted to objectively measure sleep behavior after MHI. In the acute phase after head injury in children, Lenard and Pennigstroff [7] found an increase in stage 2 (“light sleep”) and a decrease in stages 3-4 (“deep sleep”) with no consistent changes in percentage of rapid eye movement (REM) sleep. They also found more spindle activity in stages 2-3 and increased REM density. In contrast, Harada et al. [8] found a decrease in spindles and K-complexes during NREM sleep and decreased REM activity. Enomoto et al. [9] reported EEG changes in 42.5% of 280 children under 15 years of age in the acute phase after MHI. EEG abnormalities included an increase in slow-wave activity (associated with deep sleep) that had resolved during follow-up examinations. Parsons et al. [10] found similar results among adolescents with MHI.
All of the above-mentioned findings refer to the effects of MHI on sleep in the acute phase. The long-term effects of MHI on sleep in adolescents have not yet been studied consistently. Thus the purpose of our study was to characterize subjective and objective sleep abnormalities of adolescents who had experienced MHI and consequently complained of sleep disorders at the chronic phase after the injury.
Section snippets
Subjects
The patients were selected from the archives of Rambam Medical Center in Haifa, a tertiary hospital, which is the largest in the north of Israel. The study was approved by the Human Subject Committee of the hospital. A list was formed of all patients 10-18 years of age who had been admitted to the hospital between the years 1993 and 1996 after MHI (ICD-10 code S06.0) with a GCS of 13 or above on admission to the emergency department. A telephone survey of 50 of these patients was conducted
Questionnaire
Table 1 lists the responses (ranging from 0 = “none” to 4 = “extremely severe”) of our patients to questions related to the postconcussive syndrome. Results ranging from 2-4 were considered moderate to extremely severe and were therefore significant. Sixty-three percent of the subjects complained of significant amnesia regarding the MHI event but fewer complained about retrograde amnesia or amnesia of events after the head injury. Seventy-four percent of the subjects complained of significant
Discussion
This study demonstrates that 3 years after a MHI without any important known clinical consequence, adolescents complained of significant sleep disturbances that were validated by objective sleep monitoring. Both polysomnography and home actigraphy revealed similar results, including decreased sleep efficiency, with increased wake time and more frequent prolonged awakenings from sleep in the study group. Because sleep latency was similar in both study and control groups, it is likely that the
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