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Focal pathological startle following pontine infarction
Shaun R D Watson1, James G Colebatch
1Institute of Neurological Sciences, Department of Neurology and Clinical School, Prince of Wales Hospital, Randwick, Sydney 2031, Australia.
Summary
A stroke survivor experienced an abnormal, exaggerated startle reflex in his right arm. This case expands the known spectrum of acquired startle disorders following brain injury.
Area of Science:
- Neuroscience
- Neurology
- Clinical Electrophysiology
Background:
- Pontine infarction can lead to diverse neurological deficits.
- Acquired startle disorders are rare but can significantly impact quality of life.
Observation:
- A 36-year-old male presented with acute right hemiparesis due to left pontine infarction.
- Two months post-stroke, he developed sudden, involuntary right elbow flexion triggered by loud noise.
Findings:
- Electrophysiological studies revealed a large, short-latency (39 ms) synchronous discharge in the right biceps brachii upon auditory stimulation (120 dB, 1 kHz tone burst).
- The response showed rapid habituation with short interstimulus intervals (30 seconds).
- Longer-latency, less synchronous activity was observed in other ipsilateral arm muscles and contralateral muscles during voluntary contraction.
Implications:
- This case suggests a focally enhanced startle response, potentially linked to pontine lesion.
- The findings broaden the understanding of acquired startle disorders and their varied clinical presentations.
- This highlights the importance of detailed electrophysiological assessment in evaluating unusual post-stroke neurological phenomena.