Dizziness and unsteadiness associated with reports of visual disturbances and loss of balance are common complaints in those with persistent whiplash associated disorders (WAD). A number of causes for these symptoms have been suggested, but it is feasible that dizziness is a consequence of abnormal afferent input to the postural control system due either to damage to the central nervous system, the peripheral vestibular system and or abnormal cervical afferent input.
The aim of this thesis was to identify, more precisely, the nature and possible aetiology of the symptoms of dizziness and unsteadiness in subjects with whiplash as well as investigate any physical impairments of postural control, particularly with respect to abnormal cervical afferent input. A better understanding of the causes and relationships of such persistent problems was considered vital to guide physiotherapists towards suitable diagnostic measures and relevant rehabilitation.
The series of studies in this thesis investigated the symptom of dizziness and disturbances to postural control in subjects with persistent WAD and for the first time, took into consideration such factors as medication, anxiety, age and compensation status. Three tests which were likely to reflect disordered cervical afferent input were examined: cervical joint position error (JPE), an eye movement control measure, the smooth pursuit neck torsion test (SPNT) and measurement of dynamic balance control via computerised dynamic posturography. Comparison was made between subjects with whiplash complaining of dizziness and those not complaining of these symptoms. Relationships between cervical JPE, balance and SPNT were investigated. A final study was conducted in which subjects with known pure peripheral unilateral vestibular loss were examined to assess the potential of these tests to differentiate between cervical and vestibular involvement.
The results of the studies demonstrated that impairments identified in cervical JPE, balance and SPNT are common in subjects with persistent WAD who both do, and do not, complain of specific symptoms such as loss of balance or dizziness. Deficits in all three measures were greater in subjects with the symptomatic complaints of dizziness or unsteaduiess. The complaint of dizziness and the deficits in postural control could not be attributed to medications, compensation, anxiety or age. Only weak relationships were observed between cervical JPE, balance and SPNT, implying a need to assess all three measures to identify and manage disturbances in the postural control system in subjects following a whiplash injury. Further the SPNT and selected balance tests were shown to effectively differentiate between subjects with whiplash and subjects with discreet unilateral vestibular loss. Tests of cervical joint position error did not differentiate between the groups.
The results suggest that the reported characteristics of dizziness and causes of postural control disturbances in subjects with WAD are different to those with discreet vestibular pathology. The most plausible primary cause of the disturbances in subjects with WAD is abnormal cervical afferent to the postural control system.
This series of studies has been the first comprehensive investigation of factors associated with the symptom of dizziness and disturbances to postural control in subjects with persistent WAD. This research is a vital step towards early identification of the most appropriate assessment and management strategies for patients with complaints of dizziness and/or disturbances in postural control following a whiplash injury. Early recognition of these disturbances may ultimately assist in the prevention of some of the persistent complaints and physical impairments following a whiplash injury.