Traumatic Brain Injury (TBI) has been defined as damage to the brain, resulting from an external force such as an impact, penetration from a projectile object, rapid acceleration/deceleration forces, or blast waves. Brain function can be disrupted temporarily or permanently, and structural damage may or may not be identified using current imaging techniques. Given the trauma to the head and the location of the vestibular end organs, TBI can result in vestibular impairment. The impairment may be caused by peripheral damage to the end organ, central damage at the cerebellar or cortex level, or a combination of both. This chapter outlines the unique considerations for the management of those with vestibular impairment and TBI.
Traumatic brain injury results in damage that ranges from mild to severe injury. Classification of the severity of TBI can be described as mild, moderate, or severe based on Glasgow Coma Scale (GCS) ratings, the presence of loss of consciousness (LOC), or post-traumatic amnesia (PTA). See Table 26-1 for the classification structure that is most commonly described. Neither the location of the lesion, nor the nature of resulting impairment factors into the severity classification.1
Table 26-1SEVERITY CLASSIFICATION FOR TRAUMATIC BRAIN INJURY |Favorite Table|Download (.pdf) Table 26-1 SEVERITY CLASSIFICATION FOR TRAUMATIC BRAIN INJURY
| ||Mild ||Moderate ||Severe |
|Glasgow Coma Scale ||13–15 ||9–12 ||3–8 |
|Loss of consciousness ||0–30 minutes ||<30 minutes to <24 hours ||>24 hours |
|Post-traumatic amnesia ||<1 day ||>1 day but <7 days ||>7 days |
The term concussion, used interchangeably with mild traumatic brain injury (mTBI), describes a complex pathophysiological process that affects the brain. This process is induced by traumatic biomechanical forces, but does not require direct contact to the head. For example, blast exposure can cause concussion, as can a fall that results in rapid acceleration/deceleration of the head but no direct contact between the head and the ground. Concussion causes a rapid onset of short-lived impairments of neurological function that usually resolve spontaneously. Loss of consciousness may or may not be present with a concussion.2,3
The diagnostic criteria for post-concussive syndrome (PCS) have been defined by several groups, including the World Health Organization (WHO) for the ICD-10 coding system, and the American Psychiatric Association for the DSM-IV. These criteria differ in their inclusiveness (Box 26-1) and have since been found to be flawed.4–6 The Centers for Disease Control (CDC) defines PCS as having a prolonged recovery, and generally the period of 3 months is used to separate acute concussion from PCS.3 There is little consensus or published literature that states a clear delineation between mTBI or concussion and PCS.
Box 26-1 CURRENT DEFINITIONS ...