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Neurological Rarities |
* Specialist Registrar in Neurology, Department of Neurology, Gloucester Royal Hospital, Great Western Road, Gloucester, GL1 3NN; E-mail: ajlindahl{at}hotmail.com
EXTRACT
INTRODUCTION
We are all personally familiar with the startle response the abrupt start or jump in response to sudden unexpected stimuli, like a loud noise. This startle is a nonsuppressible reflex, which alerts us to abrupt changes in our environment that may threaten our safety. It is a reflex with survival value. But, if excessive or too easily triggered, it can interfere with daily functioning, or cause falls or injuries, and it is then a pathological response. The startle reflex is thought to be mediated at the level of the midbrain or below, because it is still elicited in decerebrate animals (Forbes & Sherrington 1914). The intensity of the startle reflex in humans varies between individuals and is increased by anxiety, fatigue or emotion (consider your response to a door slamming as you are watching a late night horror movie).
Pathological startle syndromes can be divided into (Fig. 1):
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