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Progression after chronic manganese exposure
1Department of Neurology, Chang Gung Medical College and Memorial Hospital, Taipei, Taiwan.
Abstract:
We report a longitudinal follow-up study on six patients with chronic manganese-induced parkinsonism following cessation of manganese exposure. Compared with the 1987 study, their parkinsonian symptoms showed a slow progression, particularly in gait disturbances such as freezing during turning and walking backward with retropulsion. The mean disability scores on the King's College Hospital Rating Scale were 15.0 +/- 4.2 in 1987 and 28.3 +/- 6.7 in 1991 (p = 0.003, paired t test). Review of the video records also confirmed a worsening of parkinsonism, especially in difficulty turning. Three of six patients receiving levodopa treatment had an initial improvement. The response decreased after 2 to 3 years. During the therapy, they did not develop on-off fluctuation or dyskinesia. We conclude that patients with manganese-induced parkinsonism may develop increasing neurologic dysfunction long after cessation of exposure and that their responses to levodopa are different from those of patients with Parkinson's disease.
Insights
Chronic manganese exposure causes parkinsonism with progressive symptoms, even after exposure stops. Levodopa treatment offers limited, temporary relief in these patients.
Area of Science:
- Neurology
- Environmental Health
- Toxicology
Background:
- Manganese exposure can lead to parkinsonism, a neurological disorder.
- Longitudinal studies are crucial for understanding disease progression after exposure cessation.
Purpose of the Study:
- To assess the long-term progression of parkinsonian symptoms in patients after stopping manganese exposure.
- To evaluate the efficacy and duration of levodopa treatment in manganese-induced parkinsonism.
Main Methods:
- Longitudinal follow-up of six patients with chronic manganese-induced parkinsonism.
- Clinical assessment of parkinsonian symptoms and disability scores (King's College Hospital Rating Scale).
- Video recording analysis to confirm symptom progression, particularly gait disturbances.
Main Results:
- Parkinsonian symptoms, especially gait issues like freezing and retropulsion, showed slow but significant progression over time.
- Mean disability scores increased from 15.0 in 1987 to 28.3 in 1991 (p=0.003).
- Levodopa provided initial improvement in three patients, but the response diminished within 2-3 years without causing dyskinesia or on-off fluctuations.
Conclusions:
- Manganese-induced parkinsonism can lead to worsening neurological dysfunction years after manganese exposure ceases.
- Patients with manganese-induced parkinsonism exhibit distinct responses to levodopa compared to those with idiopathic Parkinson's disease.