SIR: Manganese intoxication is a well-known cause of parkinsonism and dementia.1 It affects welders, miners, steelworkers, and workers in other occupations. The presenting signs of chronic manganism include disorientation, impairment of memory and judgment, acute anxiety, emotional lability, compulsive acts, hallucinations, illusions, and delusions. Extrapyramidal syndromes resembling Parkinson's disease include characteristic neurologic manifestations.1,2 The underlying mechanisms whereby manganese develops toxicity are unknown. The diagnostic hallmarks are occupational exposure, a compatible clinical syndrome, and high levels of manganese in blood or urine. T1-weighted MRI has been reported to be useful in the diagnosis of manganese intoxication because of high signal intensity areas in the basal ganglia.3
We describe a 14-year follow-up of a chronic enteral manganese poisoning. A 66-year-old male patient with proven manganese poisoning was treated in our hospital. The complete case was published in 1986.4 Fourteen years after the intoxication, the now 80-year-old patient is still alive. We examined the patient in our hospital again. Clinical, neurological, and psychiatric examinations were performed in the same manner described before.4
The patient was alert, oriented, and coherent but slow in mentation. His speech was slightly dysarthric, and a shortening of the patient's gait was noticed. The gastrocnemius tendon reflex was reduced bilaterally, hemihypesthesia was reported in both hands, and there was a diminished perception of vibration of the lower extremities symmetrically. Coordination was impaired. He showed no rigor but manifested a low-grade resting tremor and ubiquitous muscle fasciculations of variable intensity at the upper extremities. He displayed no evidence of hallucinations or delusions. He still complained of disturbances of concentration. Fasting blood samples were collected for all routine analyses, the results of which were normal. Cranial MRI revealed no abnormalities, as has been described by others.3
The clinical summaries of the patient's symptoms from 1984 to 1998 were compared. Most symptoms improved, including disturbances such as rigor, muscle pain or cramps, hypersomnia, increased libido, sweating, fatigue, concentration, and anxiety. Most extrapyramidal syndromes resembling Parkinson's disease are unchanged; we did not notice a deterioration of these symptoms. Thus, we observed no long-term progression of the parkinsonian syndrome as described by others.5 During the acute stage, high levels of manganese concentration were found in blood (150 μg/l; reference level 7.1—10.5 μg/l) and scalp hair (1.6 μg/g; reference level 0.07—1.00 μg/g). The blood manganese concentration now is reduced under the normal range (4.8 μg/l), whereas the manganese concentration in scalp hair (2.79 μg/g) has kept on increasing. We did not find a reduced manganese concentration in scalp hair in comparison to former studies.5
Long-term progression in chronic manganism might possibly occur,5 but this seems to be facultative. We did not find high signal intensity in the basal ganglia on T1-weighted images, though this was often observed by others.3 Further investigations would be useful to clarify the role of MRI as a diagnostic hallmark in chronic manganism.