Audiologic and cognitive long-term sequelae from closed head injury

Sammanfattning: Objectives – Head injury is an important health problem all over the world. Previous studies have shown that peripheral hearing impairment (HI) is a common sequel of closed head injury (CHI), but in most cases it will subside within the first posttraumatic months. However, in some cases, the HI persists and in other cases there can even be progress. The objective of the present study was to analyse long-term audiologic and cognitive consequences of CHI.There were four main issues:1. To study the presence and progress of sensorineural hearing loss (SNHL) after CHI and whether prediction of progress is possible. Autoimmunity as a possible cause of progress is also investigated, and the question of sympathetic cochleolabyrinthitis is discussed.2. To study the presence of central auditory processing disorders (CAPD) after CHI; the question of a King-Kopetzky syndrome should be discussed.3. To study the presence of cognitive impairments.4. To evaluate self-assessed hearing, cognition and quality of life from a long-term perspective.Material and methods – During a period of 14 years, around 2000 patients with head injuries were admitted to the emergency ward at Lindesberg County Hospital and Örebro Medical Centre Hospital. Six hundred subjects suffered from skull fracture and/or brain contusion and diagnosis was established using a computed tomography scan (CT). The degree of initial brain injury was estimated using the Swedish Reaction Level Scale (RLS). Sixty-six subjects were investigated with pure tone audiometry in close proximity to the trauma, and this gave an opportunity to study the issue of progress. The investigation took place two to 14 years after trauma, and the results were compared to matched control groups. A battery of different audiological methods was used to investigate peripheral and central auditory function, and a specially designed acoustic environmental room was also utilized. Cognition was investigated using a computer-based test-battery, text information process system (TIPS). Self-assessed hearing, cognition and quality of life were explored using different questionnaires.Results – A high percentage of peripheral and central auditory impairments and also cognitive shortcomings were demonstrated. Progress of SNHL was a common finding, and fracture, high age at trauma and large initial hearing loss predicted progress. Antibody-mediated autoimmunity as a mechanism behind posttraumatic progress of SNHL or clear evidence for sympathetic cochleolabyrinthitis could not be demonstrated. Binaural auditory deficits could be demonstrated when tested in a realistic acoustic environment. Tinnitus, vertigo and memory shortcomings proved to be common sequelae, even in a long-term perspectiveCognitive shortcomings were found in several of these well-rehabilitated subjects.On a group level, there was a good correlation between self-assessments and audiometric results, even if some individuals had a tendency to over- or underestimate their abilities.Conclusion – Auditory and cognitive long-term sequelae of CHI are a common finding even in well-rehabilitated and socially well-functioning subjects, as are vertigo and tinnitus. Vertigo and tinnitus are also common sequelae after CHI, therefore a basic audiovestibular investigation after CHI is recommended, at least in selected cases.Early awareness of the risk for hearing and cognitive sequelae after CHI could lead to measurements taken to prevent tension-related symptoms.Early detection of HI offers an opportunity to try immunosuppressive treatment in cases with a large initial SNHL.