A psychophysical method for assessing visual and acoustic hyperaesthesia in patients with mild head injury.

Although it is well known that patients with mild head injury (MHI) are less able to endure intense light and sound stimuli than normal people, there are few psychophysical studies that have objectively measured this type of hyperaesthesia. In the present study, using a computerised rating scale technique, both the maximal and submaximal levels of reduced tolerance to light and sound were assessed for a wide range of stimuli. Three to six days after the trauma, 40 MHI patients were significantly less tolerant to stimuli of intensities over 71 dB and 500 lux levels than controls. These intensities are common, and MHI patients may suffer as a consequence.