Abstract

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):

• Primary