Blast exposure and dual sensory impairment: An evidence review and integrated rehabilitation approach

Abstract

Abstract-Combat exposures to blast can result in both peripheral damage to the ears and eyes and central damage to the auditory and visual processing areas in the brain. The functional effects of the latter include visual, auditory, and cognitive processing difficulties that manifest as deficits in attention, memory, and problem solving-symptoms similar to those seen in individuals with visual and auditory processing disorders. Coexisting damage to the auditory and visual system is referred to as dual sensory impairment (DSI). The number of Operation Iraqi Freedom/Operation Enduring Freedom Veterans with DSI is vast; yet currently no established models or guidelines exist for assessment, rehabilitation, or service-delivery practice. In this article, we review the current state of knowledge regarding blast exposure and DSI and outline the many unknowns in this area. Further, we propose a model for clinical assessment and rehabilitation of blast-related DSI that includes development of a coordinated team-based approach to target activity limitations and participation restrictions in order to enhance reintegration, recovery, and quality of life.

Auditory difficulties in blast-exposed Veterans with clinically normal hearing

“…As seen in Tables 3 and 4, participants perceived considerable hearing difficulty, such that their FHQ and SSQ questionnaire scores were more like those of older individuals with hearing impairment * [27], than they were to individuals of equivalent age and normal hearing sensitivity [9,42]. A similar finding was reported in a population of OIF Veterans with blast-related TBI, among whom 11 percent reported hearing difficulties yet had clinically normal hearing [12] and in a survey of VA audiologists that found that 92 percent of audiologists encountered at least one OIF/OEF Veteran a month who had difficulties hearing and yet had normal or almost normal pure tone sensitivity, with 53 percent of audiologists encountering between one and three per month and 39 percent encountering four or more per month [14].…”

“…In addition to typical postconcussive symptoms, many blast-exposed Veterans report difficulty understanding speech in noise and problems with auditory memory yet have no measureable peripheral auditory deficits [12][13][14]. Some authors have concluded that these auditory complaints reflect symptoms primarily associated with posttraumatic stress disorder (PTSD) [15], while others suggest they are associated with blastrelated TBI [16], and more specifically, blast-related damage to the central auditory system [11][12][17][18].…”

“…In 2010, an informal survey of VA audiologists found that 92 percent encountered at least one OIF/OEF/OND Veteran per month who had difficulties hearing and yet had normal or almost normal pure tone sensitivity, with 53 percent of audiologists encountering between one and three per month and 39 percent encountering four or more per month [14]. In terms of clinical management for these individuals, no approaches have an evidence base.…”

Implications of blast exposure for central auditory function: A review

“…The guidelines that do exist emphasize the individualized nature of the treatment plan and the importance of working with a team of specialists [58][59], which is especially important for Veterans with multiple war-related injuries. A recent survey described by Saunders and Echt found that, although nearly all of the VA audiologists who responded had experiences in which OIF/OEF Veterans with normal audiograms complained of difficulties hearing, there was no clear consensus as to what treatment to offer [65]. Treatment approaches described included hearing aids, remotemicrophone technology, and auditory training.…”

“…As described in the section on proposed treatment options, one indication that central auditory dysfunction may be more prevalent than is currently known comes from the survey reported by Saunders and Echt [65]. In the spring of 2009, 220 VA audiologists who subscribe to the VA audiology email list were asked "How often do you encounter OIF/OEF Veterans complaining of hearing difficulties who have normal or almost normal thresholds?"…”