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Hyperbaric hyperreflexia: tendon-jerk and Hoffmann reflexes in man at 43 bars
Electroencephalography and Clinical Neurophysiology
|December 1, 1979
Summary
This study investigated neuromuscular reflexes in divers during a simulated deep-sea dive. Findings show altered reflex responses and abnormal muscle activity under hyperbaric conditions, suggesting potential neurological effects.
Area of Science:
- Neurology
- Physiology
- Hyperbaric Medicine
Background:
- Understanding neuromuscular function under extreme pressure is crucial for deep-sea exploration safety.
- Previous research on hyperbaric effects on reflexes is limited.
Purpose of the Study:
- To investigate changes in soleus muscle reflexes during a simulated oxygen-helium dive.
- To analyze the impact of hyperbaric exposure on neuromuscular excitability and reflex arcs.
Main Methods:
- Studied tendon jerk (TJR) and Hoffmann (H) reflexes in two subjects during a 26-day dive simulation to 43 bars.
- Utilized excitability cycles (twin-pulses) and analyzed electromyographic (EMG) recordings.
- Assessed responses to Jenkdrassik's manoeuvre.
Main Results:
- Observed a biphasic increase in TJR amplitude post-compression and during decompression, mirrored by H reflex changes.
- Noted reduced facilitatory and increased inhibitory effects of Jenkdrassik's manoeuvre under hyperbaric conditions.
- Documented altered excitability cycles, abnormal EMG potentials, and late reflex responses.
Conclusions:
- Hyperbaric exposure significantly alters neuromuscular reflex activity in the soleus muscle.
- Findings suggest potential modifications in vestibulo-spinal relations and presynaptic inhibition.
- Abnormal EMG findings indicate complex neurological responses to extreme pressure environments.