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The palmo-mental reflex in vibroacoustic disease
A J Martinho Pimenta1, M S Castelo Branco, N A Castelo Branco
1Santo António dos Capuchos Hospital, Lisbon, Portugal.
Aviation, Space, and Environmental Medicine
|April 3, 1999
Summary
Vibroacoustic disease (VAD) patients often show abnormal chin muscle activity, even without the visible palmomental reflex (PMR). This indicates a loss of cortical control in VAD, highlighting the need for further neurological assessment.
Area of Science:
- Neurology
- Occupational Health
- Acoustic Medicine
Background:
- Vibroacoustic disease (VAD) is a condition resulting from occupational exposure to high-amplitude, low-frequency noise (LPALF).
- The palmomental reflex (PMR), a primitive reflex, is a common neurological finding in VAD patients.
- Assessing PMR frequency and characteristics in VAD patients is crucial for understanding disease progression.
Purpose of the Study:
- To determine the frequency and characteristics of the palmomental reflex (PMR) in individuals with Vibroacoustic disease (VAD).
- To investigate the relationship between PMR and other neurological findings in VAD patients.
Main Methods:
- A neurological examination was conducted on sixty individuals occupationally exposed to LPALF noise.
- Chin muscle contraction was triggered by thenar eminence stimulation, with EMG used to detect subclinical responses.
- Brain MRI and endogenous evoked potentials were also assessed.
Main Results:
- Thirty VAD patients (50%) exhibited unilateral or bilateral PMR.
- Twenty-six of those with PMR showed abnormalities on brain MRI.
- EMG revealed continuous chin muscle activity without visible PMR in some subjects, indicating subclinical muscle activation.
Conclusions:
- Palmomental reflex (PMR) is present in 50% of Vibroacoustic disease (VAD) patients.
- Abnormal chin muscle activity, detected via EMG, occurs more frequently than visible PMR in VAD patients.
- This suggests a loss of cortical control over brainstem structures in VAD.