Manganism

Manganism. or hypermanganesemia, is the inherited or acquired clinical syndrome resulting from acute or chronic overexposure to the transition metal manganese, one of the essential trace elements. It primarily manifests as parkinsonism and may be clinically, radiologically and histopathologically indistinguishable from idiopathic Parkinson disease ¹. 

Clinical presentation

• parkinsonism ^3,5

  • rigidity

  • bradykinesia

  • rest tremor, although this is often atypical

  • postural instability, with an earlier propensity to fall backwards

• other features ³

  • dystonia, including the "cock-walk" gait pattern

  • polycythemia (in genetic forms)

  • chronic liver disease and cirrhosis (in genetic forms)

Pathology

Manganese is an essential trace element with a vital role in the synthesis of several key enzymes, vitamin B complex and vitamin C, as well as several other substrates. However certain occupations, especially welders, can be exposed to toxic levels of the element.

While the condition is usually acquired, manganism can also be inherited through autosomal recessive mutations ^3,5:

• SLC30A10, which codes for a manganese efflux transporter, resulting in hypermanganesemia with dystonia 1

• SLC39A14, which codes for a manganese uptake transporter, resulting in hypermanganesemia with dystonia 2

Radiographic features

MRI

• T1: hyperintense signal in the globus pallidi bilaterally

• T2: normal signal in the globus pallidi

The degree of T1 hyperintensity can be quantified as the pallidal index (PI). The pallidal index approximately correlates to the lifetime exposure and level of serum manganese ².

Treatment and prognosis

Management options include ^3-5:

• removal of exposure in acquired cases

• chelation therapy, e.g. ethylenediaminetetraacetic acid (EDTA)

• sodium para-aminosalicylic acid (PAS)

• symptomatic management of parkinonism