It usually affects a middle-aged to older adult but can affect a young patient.
The onset may be 2 to 26 weeks after the carbon monoxide exposure.
Clinical features:
(1) gait disturbance (short step gait, ataxia, other)
(2) mutism
(3) impaired cognitive function
(4) urinary and/or fecal incontinence
(5) hypokinesia
(6) masked face
(7) muscle rigidity (increased muscle tone)
(8) glabella sign (tapping a finger on the glabella triggers persistent blinking)
(9) grasp reflex
(10) retropulsion (tendency to walk backwards)
(11) variable intention tremor
(12) variable response to levodopa or anticholinergic drugs (some respond but many do not)
(13) mood disorder
Brain imaging may show:
(1) lesions in the basal ganglia (globus pallidus, putamen, caudate)
(2) multifocal lesions in the subcortical white matter
Sohn et al correlated white matter lesions seen on proton magnetic resonance spectroscopy (MRS) with the development of Parkinsonism. Demonstration of pure demyelination was associated with a delayed progressive course (see below), while damage to the axis cylinder was associated with a progressive course.
The prognosis is good with most patients recovering within 6-12 months (delayed relapsing type), but a small percent have persistent or progressive disease (progressive type).
