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The incidence of dizziness and dysequilibrium following head and/or neck injury lies between 40-60%, even following mild or moderate head injuries not requiring acute hospitalization. Accordingly, most practitioners should have a fairly extensive experience with this large outpatient group. Yet, in spite of their familiarity with this common problem, many clinicians routinely use a diagnostic approach which is not pathophysiologically based and a treatment approach which is often confined to attempts at providing symptomatic relief with vestibular suppressants. Indeed, the tendency to attribute most post-traumatic dizziness to the post-concussion syndrome without diagnostic consideration of specific vestibular pathologies has been the cause of a significant and largely unnecessary increase in morbidity in this population. What follows is a review of those specific pathologies which, taken together, cause the great proportion of post-traumatic symptoms and which should rightly form the basis for a diagnostic and management approach.
TEMPORAL BONE FRACTURE
Fractures of the temporal bone occur in the more severe cases of head injury and have a number of clinical and radiological manifestations. They represent what should be an easily identifiable subgroup of head trauma patients discharged from acute hospitals in whom residual vestibular and/or auditory system symptoms can be expected to occur in high incidence (upwards of 95% in certain types of fractures). These symptoms commonly persist well beyond the period of acute hospitalization, and as such will most often require active (and possibly long-term) management by outpatient primary and specialty caregivers.1
Basal skull fractures may be of two kinds depending upon the relationship of the fracture line to the long axis of the petrous bone. These fractures can be well demonstrated on thin section temporal bone CT. Eighty percent are longitudinal and twenty percent are transverse. As longitudinal fractures run thru the axis of the middle ear, they often produce tympanic membrane tears with otorrhagia, and conductive or mixed hearing loss. They also can cause facial palsies. Given that the fracture line does not directly involve the inner ear, vestibular symptoms are somewhat less common in this type of fracture, but they can often occur due to concurrent labyrinthine concussion, perilymphatic fistula, or benign paroxysmal positional vertigo (see below). Transverse fractures extend thru the inner ear and produce damage to cochlear and/or vestibular labyrinthine...