Hamish G. MacDougall

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Freezing of gait (FOG) is common in advanced Parkinson's disease (PD), is resistant to treatment and negatively impacts quality of life. In this study an ambulatory FOG monitor was validated in 11 PD patients. The vertical linear acceleration of the left shank was acquired using an ankle-mounted sensor array that transmitted data wirelessly to a pocket PC(More)
BACKGROUND The head impulse test (HIT) is a useful bedside test to identify peripheral vestibular deficits. However, such a deficit of the vestibulo-ocular reflex (VOR) may not be diagnosed because corrective saccades cannot always be detected by simple observation. The scleral search coil technique is the gold standard for HIT measurements, but it is not(More)
OBJECTIVE To provide the empirical basis for using ocular vestibular evoked myogenic potentials (oVEMPS) in response to Fz bone conducted vibration (BCV) stimulation to indicate vestibular function in human subjects. To show the generality of the response by testing a large number of unselected healthy subjects across a wide age range and the repeatability(More)
Laboratory studies have suggested that the preferred cadence of walking is approximately 120 steps/min, and the vertical acceleration of the head exhibits a dominant peak at this step frequency (2 Hz). These studies have been limited to short periods of walking along a predetermined path or on a treadmill, and whether such a highly tuned frequency of(More)
BACKGROUND The video head impulse test (vHIT) is a useful clinical tool to detect semicircular canal dysfunction. However vHIT has hitherto been limited to measurement of horizontal canals, while scleral search coils have been the only accepted method to measure head impulses in vertical canals. The goal of this study was to determine whether vHIT can(More)
 This study was designed to measure ocular movements evoked by galvanic (DC) stimulation using computerised video-oculography. Long duration (>30 s) galvanic vestibular stimulation at currents of up to 5 mA through large-area surface electrodes over the mastoid processes causes maintained changes in the ocular torsional position of both eyes in healthy(More)
A new system for long-term monitoring of gait in Parkinson's disease (PD) has been developed and validated. The characteristics of every stride taken over 10-h epochs were acquired using a lightweight ankle-mounted sensor array that transmitted data wirelessly to a small pocket PC at a rate of 100 Hz. Stride was calculated from the vertical linear(More)
We have previously published a technique for objective assessment of freezing of gait (FOG) in Parkinson's disease (PD) from a single shank-mounted accelerometer. Here we extend this approach to evaluate the optimal configuration of sensor placement and signal processing parameters using seven sensors attached to the lumbar back, thighs, shanks and feet.(More)
In this study the effect of a pseudorandom binaural bipolar Galvanic stimulus generated by a sum of nonharmonically related sine waves on postural control was functionally assessed using computerized dynamic posturography (CDP), and the results compared to vestibulopathic patient populations and astronauts exposed to microgravity. The standardized CDP test(More)
HYPOTHESIS That disease or dysfunction of vestibular end organs in human patients will reduce or eliminate the contribution of the affected end organs to the total eye-movement response to DC surface galvanic vestibular stimulation (GVS). BACKGROUND It was assumed that DC GVS (at current of 5 mA) stimulates all vestibular end organs, an assumption that is(More)