Manganism Diagnosis May Be Tricky
Manganism is a disease of the nervous system that causes tremors, odd movements, a mask-like face, and body stiffness. Some patients even experience hallucinations, confusion, and memory loss. Also known by the more descriptive name, “manganese poisoning,” manganism is caused by breathing in manganese. Welders develop the condition through their exposure to manganese-containing welding fumes.
Patients with manganism may experience intention tremors which are tremors that happen during movement. They may also walk with a type of staggering gait called a “cock walk.” Some doctors have contrasted these signs of manganism to symptoms experienced by Parkinson’s disease patients, who tend to have eresting tremors or shaking when there is no attempted movement. Later studies have found, however, that manganese-exposed welders may have resting tremors similar to those found in patients with Parkinson’s disease, implying an overlap between the two diseases.
Welders exposed to manganese may develop psychological difficulties, including anxiety, nervousness, memory loss, learning problems, and aggressive behavior. Some researchers have suggested using a battery of standard psychological tests to look at the extent of the problems caused by manganese exposure (Int J Hyg Environ Health 2003 Oct; 206(6): 517–29).
How Manganism Affects the Brain
Manganism mainly affects the basal area of the brain known as the “globus pallidus” that is involved in the control of movement. Nerve cells in this area degenerate or are lost completely, according to some reports. Researchers have also found that manganese exposure may damage the “substantia nigra” an area of the brain that is affected by Parkinson’s disease. This suggests that manganese exposure has a role in the development of Parkinson’s disease.
If you have been exposed to welding fumes, and have movement and balance problems, your doctor may ask you to undergo a magnetic resonance imaging (MRI) scan of your brain in order to look at the globus pallidus, substantia nigra, and other areas. Rather than using x-rays or other radiation, an MRI uses magnetic fields, radio waves, and a computer to create images. See Magnetic Resonance Imaging if you would like details about how an MRI works.
An MRI scan is painless but noisy, so you may want to wear earplugs during this test. You will also have to take off any jewelry or metal, which could interfere with the results.
L-dopa and Manganese Poisoning
Parkinson’s patients have decreased brain levels of dopamine, a chemical that transmits signals between nerve cells and affects movement. Parkinson’s patients respond well to treatment with L-dopa or levodopa, a precursor of dopamine. Levodopa seems to have little or no effect on manganism sufferers, according to some studies.
In contrast, other reports show that welders exposed to manganese fumes may respond in a way that is similar to those with Parkinson’s disease. A landmark study at Washington University School of Medicine in Missouri tested non-welders with Parkinson’s disease as well as 15 career welders exposed to manganese. The welders responded favorably to levodopa, and there was no difference in tremor, slowed movements, rigidity, or balance between the two groups. The welders developed Parkinson’s disease at around 46 years of age, while the non-welders developed the illness at around the age of 63 years. The study suggests that exposure to manganese may increase the risk of developing Parkinson’s disease, especially at an early age, and that there is some overlap between Parkinson’s disease and manganism.
PET Scans and Manganism
Positron emission tomography (PET) is a process that measures biochemical changes as well as providing images. The patient is given a common compound that is tagged with a radioisotope. A type of camera/scanner may follow how and where the compound builds up in the brain. (See a discussion by the Center for Positron Emission Tomography University of Buffalo.)
Positron emission tomography (PET) scans can show if a patient has decreased L-dopa and dopamine levels that indicate Parkinson’s disease. They may also indicate other brain abnormalities due to Parkinson’s-like symptoms. Some research indicates that PET scans can be used to distinguish between Parkinson’s disease and manganism, while recent reports suggest that the two conditions overlap.
A PET scan is not yet a standard procedure in diagnosing patients suffering from manganese exposure. If your doctor does decide to give you a PET scan, you should be aware that the test is neither noisy or intrusive. The scan generally takes about one and a half hours to 3 hours, depending upon the type of scanner.
Manganese in Blood and Urine
Blood and urine tests may show increased manganese exposure levels in patients with manganism. The normal urinary level of manganese averages about 2.75 micrograms per liter with a range of about 1.0 to 8.0 micrograms per liter, according to one source, and urinary levels over 10 micrograms per liter may indicate manganese overexposure (Risk Assessment Information System, Toxicity Summary for Manganese, Oak Ridge National Laboratory). Other sources give a normal range of 3 to 21 micrograms per liter (Manganese, WHO Publication, 1981). Some consider manganese levels in blood of over 7.5 micrograms per liter to be high. As these figures indicate, blood and urine manganese levels may be too variable to be good indicators of manganese exposure on an individual level. Also, high manganese levels in blood and urine may be temporary, and some patients show clinical symptoms of manganism without abnormal blood and urine test results.